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authorDennis Wölfing <denniswoelfing@gmx.de>2017-05-30 18:26:19 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2017-05-30 18:27:57 -0300
commit2e0bbbfbf95fc9e22692e93658a6fbdd2d4554da (patch)
tree662856c19816b2b441dbfda3e15ca771eb303e5f
parent4f26ef1b67287d1f2c32865f7d79c13abda81915 (diff)
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Add reallocarray function
The reallocarray function is an extension from OpenBSD. It is an integer-overflow-safe replacement for realloc(p, X*Y) and malloc(X*Y) (realloc(NULL, X*Y)). It can therefore help in preventing certain security issues in code. This is an updated version of a patch originally submitted by Rüdiger Sonderfeld in May 2014 [1]. Checked on i686-linux-gnu and x86_64-linux-gnu. [1] <https://sourceware.org/ml/libc-alpha/2014-05/msg00481.html>. 2017-05-30 Dennis Wölfing <denniswoelfing@gmx.de> Rüdiger Sonderfeld <ruediger@c-plusplus.de> * include/stdlib.h (__libc_reallocarray): New declaration. * malloc/Makefile (routines): Add reallocarray. (tests): Add tst-reallocarray.c. * malloc/Versions: Add reallocarray and __libc_reallocarray. * malloc/malloc-internal.h (check_mul_overflow_size_t): New inline function. * malloc/malloc.h (reallocarray): New declaration. * stdlib/stdlib.h (reallocarray): Likewise. * malloc/reallocarray.c: New file. * malloc/tst-reallocarray.c: New test file. * manual/memory.texi: Document reallocarray. * sysdeps/unix/sysv/linux/aarch64/libc.abilist: Add reallocarray. * sysdeps/unix/sysv/linux/alpha/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/arm/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/hppa/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/i386/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/ia64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/microblaze/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/nios2/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/sh/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/tilepro/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise. * sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist: Likewise.
-rw-r--r--ChangeLog45
-rw-r--r--NEWS4
-rw-r--r--include/stdlib.h4
-rw-r--r--malloc/Makefile4
-rw-r--r--malloc/Versions4
-rw-r--r--malloc/malloc-internal.h19
-rw-r--r--malloc/malloc.h8
-rw-r--r--malloc/reallocarray.c37
-rw-r--r--malloc/tst-reallocarray.c118
-rw-r--r--manual/memory.texi46
-rw-r--r--stdlib/stdlib.h11
-rw-r--r--sysdeps/unix/sysv/linux/aarch64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/alpha/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/arm/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/hppa/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/i386/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/ia64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/microblaze/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/nios2/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/sh/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/x86_64/64/libc.abilist2
-rw-r--r--sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist2
39 files changed, 344 insertions, 12 deletions
diff --git a/ChangeLog b/ChangeLog
index 92d762e..876244a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,48 @@
+2017-05-30 Dennis Wölfing <denniswoelfing@gmx.de>
+ Rüdiger Sonderfeld <ruediger@c-plusplus.de>
+
+ * include/stdlib.h (__libc_reallocarray): New declaration.
+ * malloc/Makefile (routines): Add reallocarray.
+ (tests): Add tst-reallocarray.c.
+ * malloc/Versions: Add reallocarray and __libc_reallocarray.
+ * malloc/malloc-internal.h (check_mul_overflow_size_t): New inline
+ function.
+ * malloc/malloc.h (reallocarray): New declaration.
+ * stdlib/stdlib.h (reallocarray): Likewise.
+ * malloc/reallocarray.c: New file.
+ * malloc/tst-reallocarray.c: New test file.
+ * manual/memory.texi: Document reallocarray.
+ * sysdeps/unix/sysv/linux/aarch64/libc.abilist: Add reallocarray.
+ * sysdeps/unix/sysv/linux/alpha/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/arm/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/hppa/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/i386/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/ia64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/microblaze/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/nios2/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist:
+ Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist:
+ Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/sh/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/tilepro/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise.
+ * sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist: Likewise.
+
2017-05-30 H.J. Lu <hongjiu.lu@intel.com>
* sysdeps/x86_64/memchr.S (memchr): Use 32-bit registers for
diff --git a/NEWS b/NEWS
index b4ecd62..f92392a 100644
--- a/NEWS
+++ b/NEWS
@@ -66,6 +66,10 @@ Version 2.26
* The port to Native Client running on ARMv7-A (--host=arm-nacl) has been
removed.
+* The reallocarray function has been added to libc. It is a realloc
+ replacement with a check for integer overflow when calculating total
+ allocation size.
+
Security related changes:
* The DNS stub resolver limits the advertised UDP buffer size to 1200 bytes,
diff --git a/include/stdlib.h b/include/stdlib.h
index c3ee680..5847445 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -110,6 +110,10 @@ extern int __posix_memalign (void **memptr, size_t alignment, size_t size);
extern void *__libc_memalign (size_t alignment, size_t size)
__attribute_malloc__;
+extern void *__libc_reallocarray (void *__ptr, size_t __nmemb, size_t __size)
+ __THROW __attribute_warn_unused_result__;
+libc_hidden_proto (__libc_reallocarray)
+
extern int __libc_system (const char *line);
diff --git a/malloc/Makefile b/malloc/Makefile
index d0f23f7..b7d4c63 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -26,7 +26,7 @@ dist-headers := malloc.h
headers := $(dist-headers) obstack.h mcheck.h
tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
tst-mcheck tst-mallocfork tst-trim1 \
- tst-malloc-usable tst-realloc tst-posix_memalign \
+ tst-malloc-usable tst-realloc tst-reallocarray tst-posix_memalign \
tst-pvalloc tst-memalign tst-mallopt \
tst-malloc-backtrace tst-malloc-thread-exit \
tst-malloc-thread-fail tst-malloc-fork-deadlock \
@@ -49,7 +49,7 @@ endif
tests += $(tests-static)
test-srcs = tst-mtrace
-routines = malloc morecore mcheck mtrace obstack \
+routines = malloc morecore mcheck mtrace obstack reallocarray \
scratch_buffer_grow scratch_buffer_grow_preserve \
scratch_buffer_set_array_size
diff --git a/malloc/Versions b/malloc/Versions
index e34ab17..23aafb5 100644
--- a/malloc/Versions
+++ b/malloc/Versions
@@ -62,6 +62,7 @@ libc {
aligned_alloc;
}
GLIBC_2.26 {
+ reallocarray;
}
GLIBC_PRIVATE {
# Internal startup hook for libpthread.
@@ -74,5 +75,8 @@ libc {
__libc_scratch_buffer_grow;
__libc_scratch_buffer_grow_preserve;
__libc_scratch_buffer_set_array_size;
+
+ # Internal name for reallocarray
+ __libc_reallocarray;
}
}
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
index de6103d..dbd801a 100644
--- a/malloc/malloc-internal.h
+++ b/malloc/malloc-internal.h
@@ -81,5 +81,24 @@ void __malloc_fork_unlock_parent (void) internal_function attribute_hidden;
/* Called in the child process after a fork. */
void __malloc_fork_unlock_child (void) internal_function attribute_hidden;
+/* Set *RESULT to LEFT * RIGHT. Return true if the multiplication
+ overflowed. */
+static inline bool
+check_mul_overflow_size_t (size_t left, size_t right, size_t *result)
+{
+#if __GNUC__ >= 5
+ return __builtin_mul_overflow (left, right, result);
+#else
+ /* size_t is unsigned so the behavior on overflow is defined. */
+ *result = left * right;
+ size_t half_size_t = ((size_t) 1) << (8 * sizeof (size_t) / 2);
+ if (__glibc_unlikely ((left | right) >= half_size_t))
+ {
+ if (__glibc_unlikely (right != 0 && *result / right != left))
+ return true;
+ }
+ return false;
+#endif
+}
#endif /* _MALLOC_INTERNAL_H */
diff --git a/malloc/malloc.h b/malloc/malloc.h
index 274c095..339ab64 100644
--- a/malloc/malloc.h
+++ b/malloc/malloc.h
@@ -49,6 +49,14 @@ __THROW __attribute_malloc__ __wur;
extern void *realloc (void *__ptr, size_t __size)
__THROW __attribute_warn_unused_result__;
+/* Re-allocate the previously allocated block in PTR, making the new
+ block large enough for NMEMB elements of SIZE bytes each. */
+/* __attribute_malloc__ is not used, because if reallocarray returns
+ the same pointer that was passed to it, aliasing needs to be allowed
+ between objects pointed by the old and new pointers. */
+extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
+__THROW __attribute_warn_unused_result__;
+
/* Free a block allocated by `malloc', `realloc' or `calloc'. */
extern void free (void *__ptr) __THROW;
diff --git a/malloc/reallocarray.c b/malloc/reallocarray.c
new file mode 100644
index 0000000..07562c3
--- /dev/null
+++ b/malloc/reallocarray.c
@@ -0,0 +1,37 @@
+/* Change the size of an allocated block.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <malloc.h>
+#include <malloc/malloc-internal.h>
+
+void *
+__libc_reallocarray (void *optr, size_t nmemb, size_t elem_size)
+{
+ size_t bytes;
+ if (check_mul_overflow_size_t (nmemb, elem_size, &bytes))
+ {
+ __set_errno (ENOMEM);
+ return 0;
+ }
+ else
+ return realloc (optr, bytes);
+}
+libc_hidden_def (__libc_reallocarray)
+
+weak_alias (__libc_reallocarray, reallocarray)
diff --git a/malloc/tst-reallocarray.c b/malloc/tst-reallocarray.c
new file mode 100644
index 0000000..f1cbf7f
--- /dev/null
+++ b/malloc/tst-reallocarray.c
@@ -0,0 +1,118 @@
+/* Test for reallocarray.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <malloc.h>
+#include <string.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+ void *ptr = NULL;
+ void *ptr2 = NULL;
+ unsigned char *c;
+ size_t i;
+ int ok;
+ const size_t max = ~(size_t)0;
+ size_t a, b;
+
+ /* Test overflow detection. */
+ errno = 0;
+ ptr = reallocarray (NULL, max, 2);
+ TEST_VERIFY (!ptr);
+ TEST_VERIFY (errno == ENOMEM);
+
+ errno = 0;
+ ptr = reallocarray (NULL, 2, max);
+ TEST_VERIFY (!ptr);
+ TEST_VERIFY (errno == ENOMEM);
+
+ a = 65537;
+ b = max/65537 + 1;
+ errno = 0;
+ ptr = reallocarray (NULL, a, b);
+ TEST_VERIFY (!ptr);
+ TEST_VERIFY (errno == ENOMEM);
+
+ errno = 0;
+ ptr = reallocarray (NULL, b, a);
+ TEST_VERIFY (!ptr);
+ TEST_VERIFY (errno == ENOMEM);
+
+ /* Test realloc-like behavior. */
+ /* Allocate memory like malloc. */
+ ptr = reallocarray (NULL, 10, 2);
+ TEST_VERIFY_EXIT (ptr);
+ TEST_VERIFY_EXIT (malloc_usable_size (ptr) >= 10*2);
+
+ memset (ptr, 0xAF, 10*2);
+
+ /* Enlarge buffer. */
+ ptr2 = reallocarray (ptr, 20, 2);
+ TEST_VERIFY (ptr2);
+ if (ptr2)
+ ptr = ptr2;
+ TEST_VERIFY (malloc_usable_size (ptr) >= 20*2);
+
+ c = ptr;
+ ok = 1;
+ for (i = 0; i < 10*2; ++i)
+ {
+ if (c[i] != 0xAF)
+ ok = 0;
+ }
+ TEST_VERIFY (ok);
+
+ /* Decrease buffer size. */
+ ptr2 = reallocarray (ptr, 5, 3);
+ TEST_VERIFY (ptr2);
+ if (ptr2)
+ ptr = ptr2;
+ TEST_VERIFY_EXIT (malloc_usable_size (ptr) >= 5*3);
+
+ c = ptr;
+ ok = 1;
+ for (i = 0; i < 5*3; ++i)
+ {
+ if (c[i] != 0xAF)
+ ok = 0;
+ }
+ TEST_VERIFY (ok);
+
+ /* Overflow should leave buffer untouched. */
+ errno = 0;
+ ptr2 = reallocarray (ptr, 2, ~(size_t)0);
+ TEST_VERIFY (!ptr2);
+ TEST_VERIFY (errno == ENOMEM);
+
+ c = ptr;
+ ok = 1;
+ for (i = 0; i < 5*3; ++i)
+ {
+ if (c[i] != 0xAF)
+ ok = 0;
+ }
+ TEST_VERIFY (ok);
+
+ free (ptr);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/manual/memory.texi b/manual/memory.texi
index a256ca0..fb6b594 100644
--- a/manual/memory.texi
+++ b/manual/memory.texi
@@ -751,8 +751,8 @@ be a buffer that you use to hold a line being read from a file; no matter
how long you make the buffer initially, you may encounter a line that is
longer.
-You can make the block longer by calling @code{realloc}. This function
-is declared in @file{stdlib.h}.
+You can make the block longer by calling @code{realloc} or
+@code{reallocarray}. These functions are declared in @file{stdlib.h}.
@pindex stdlib.h
@comment malloc.h stdlib.h
@@ -816,9 +816,29 @@ behavior, and will probably crash when @code{realloc} is passed a null
pointer.
@end deftypefun
-Like @code{malloc}, @code{realloc} may return a null pointer if no
-memory space is available to make the block bigger. When this happens,
-the original block is untouched; it has not been modified or relocated.
+@comment malloc.h stdlib.h
+@comment BSD
+@deftypefun {void *} reallocarray (void *@var{ptr}, size_t @var{nmemb}, size_t @var{size})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{} @acsmem{}}}
+
+The @code{reallocarray} function changes the size of the block whose address
+is @var{ptr} to be long enough to contain a vector of @var{nmemb} elements,
+each of size @var{size}. It is equivalent to @samp{realloc (@var{ptr},
+@var{nmemb} * @var{size})}, except that @code{reallocarray} fails safely if
+the multiplication overflows, by setting @code{errno} to @code{ENOMEM},
+returning a null pointer, and leaving the original block unchanged.
+
+@code{reallocarray} should be used instead of @code{realloc} when the new size
+of the allocated block is the result of a multiplication that might overflow.
+
+@strong{Portability Note:} This function is not part of any standard. It was
+first introduced in OpenBSD 5.6.
+@end deftypefun
+
+Like @code{malloc}, @code{realloc} and @code{reallocarray} may return a null
+pointer if no memory space is available to make the block bigger. When this
+happens, the original block is untouched; it has not been modified or
+relocated.
In most cases it makes no difference what happens to the original block
when @code{realloc} fails, because the application program cannot continue
@@ -838,16 +858,17 @@ xrealloc (void *ptr, size_t size)
@}
@end smallexample
-You can also use @code{realloc} to make a block smaller. The reason you
-would do this is to avoid tying up a lot of memory space when only a little
-is needed.
+You can also use @code{realloc} or @code{reallocarray} to make a block
+smaller. The reason you would do this is to avoid tying up a lot of memory
+space when only a little is needed.
@comment The following is no longer true with the new malloc.
@comment But it seems wise to keep the warning for other implementations.
In several allocation implementations, making a block smaller sometimes
necessitates copying it, so it can fail if no other space is available.
-If the new size you specify is the same as the old size, @code{realloc}
-is guaranteed to change nothing and return the same address that you gave.
+If the new size you specify is the same as the old size, @code{realloc} and
+@code{reallocarray} are guaranteed to change nothing and return the same
+address that you gave.
@node Allocating Cleared Space
@subsubsection Allocating Cleared Space
@@ -1588,6 +1609,11 @@ Malloc}.
Make a block previously allocated by @code{malloc} larger or smaller,
possibly by copying it to a new location. @xref{Changing Block Size}.
+@item void *reallocarray (void *@var{ptr}, size_t @var{nmemb}, size_t @var{size})
+Change the size of a block previously allocated by @code{malloc} to
+@code{@var{nmemb} * @var{size}} bytes as with @code{realloc}. @xref{Changing
+Block Size}.
+
@item void *calloc (size_t @var{count}, size_t @var{eltsize})
Allocate a block of @var{count} * @var{eltsize} bytes using
@code{malloc}, and set its contents to zero. @xref{Allocating Cleared
diff --git a/stdlib/stdlib.h b/stdlib/stdlib.h
index 99125f2..428ca2e 100644
--- a/stdlib/stdlib.h
+++ b/stdlib/stdlib.h
@@ -422,6 +422,17 @@ extern void *calloc (size_t __nmemb, size_t __size)
between objects pointed by the old and new pointers. */
extern void *realloc (void *__ptr, size_t __size)
__THROW __attribute_warn_unused_result__;
+
+#ifdef __USE_GNU
+/* Re-allocate the previously allocated block in PTR, making the new
+ block large enough for NMEMB elements of SIZE bytes each. */
+/* __attribute_malloc__ is not used, because if reallocarray returns
+ the same pointer that was passed to it, aliasing needs to be allowed
+ between objects pointed by the old and new pointers. */
+extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
+ __THROW __attribute_warn_unused_result__;
+#endif
+
/* Free a block allocated by `malloc', `realloc' or `calloc'. */
extern void free (void *__ptr) __THROW;
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index 58d768c..a494c39 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2097,3 +2097,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index 906050d..2fc1a9b 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2008,6 +2008,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
index 66112dd..4465a62 100644
--- a/sysdeps/unix/sysv/linux/arm/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
@@ -98,6 +98,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.4 GLIBC_2.4 A
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 3ddadd2..96126d9 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -1862,6 +1862,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index 977ab90..aae351b 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2020,6 +2020,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index c7edb9a..81ec65b 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -1884,6 +1884,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index 450be4e..9db205b 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -99,6 +99,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.4 GLIBC_2.4 A
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0x98
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index 9e016bd..ee59e95 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -1976,6 +1976,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
index 1a455be..feb8697 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
@@ -2097,3 +2097,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 8eb5e66..a5b1c42 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -1951,6 +1951,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index 416d9ac..570a859 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -1949,6 +1949,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index f4949e5..71008ad 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -1947,6 +1947,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index c7375ae..1a07d66 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -1942,6 +1942,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index 724a0e3..a62a41b 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2138,3 +2138,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index 2dc32b6..f4f11dc 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -1980,6 +1980,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index 5658109..2977569 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -1985,6 +1985,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
index c761221..271d32e 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
@@ -2185,3 +2185,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
index 265c769..372ef67 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
@@ -99,6 +99,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 _Exit F
GLIBC_2.3 _IO_2_1_stderr_ D 0xe0
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index ed1b6bf..705ff85 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -1980,6 +1980,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index 2e75d29..21fd2b5 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -1881,6 +1881,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
index bd74c0c..313a71e 100644
--- a/sysdeps/unix/sysv/linux/sh/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
@@ -1866,6 +1866,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index 5584838..94a4fb2 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -1972,6 +1972,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index efedbe2..6db5811 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -1910,6 +1910,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
index ffd988a..5d83926 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
@@ -2104,3 +2104,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
index f0c13ce..ce14ceb 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
@@ -2104,3 +2104,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
index ffd988a..5d83926 100644
--- a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
@@ -2104,3 +2104,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index f57004c..f69de7a 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -1861,6 +1861,8 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F
GLIBC_2.3 GLIBC_2.3 A
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index 05629e1..a330855 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2104,3 +2104,5 @@ GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 reallocarray F