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authorFlorian Weimer <fweimer@redhat.com>2022-12-19 18:56:55 +0100
committerFlorian Weimer <fweimer@redhat.com>2022-12-19 18:56:55 +0100
commit118816de3383ff12769349784689141355cc787c (patch)
treefa858eff7a21613e38e532ac9c1d0edd1651aeab
parent5365acc567a49270b4341b9d325794ec554258d9 (diff)
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libio: Convert __vswprintf_internal to buffers (bug 27857)
Always null-terminate the buffer and set E2BIG if the buffer is too small. This fixes bug 27857. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
-rw-r--r--elf/Makefile1
-rw-r--r--include/printf_buffer.h1
-rw-r--r--libio/tst_swprintf.c31
-rw-r--r--libio/vswprintf.c100
-rw-r--r--manual/stdio.texi7
-rw-r--r--stdio-common/wprintf_buffer_flush.c6
6 files changed, 57 insertions, 89 deletions
diff --git a/elf/Makefile b/elf/Makefile
index 36901ac..0ecbcde 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -609,7 +609,6 @@ $(objpfx)tst-relro-libc.out: tst-relro-symbols.py $(..)/scripts/glibcelf.py \
--required=_IO_wmem_jumps \
--required=_IO_wprintf_buffer_as_file_jumps \
--required=_IO_wstr_jumps \
- --required=_IO_wstrn_jumps \
--optional=_IO_old_cookie_jumps \
--optional=_IO_old_file_jumps \
--optional=_IO_old_proc_jumps \
diff --git a/include/printf_buffer.h b/include/printf_buffer.h
index 168555d..e7a45fb 100644
--- a/include/printf_buffer.h
+++ b/include/printf_buffer.h
@@ -196,6 +196,7 @@ bool __printf_buffer_flush (struct __printf_buffer *buf) attribute_hidden;
enum __wprintf_buffer_mode
{
__wprintf_buffer_mode_failed,
+ __wprintf_buffer_mode_swprintf,
__wprintf_buffer_mode_to_file,
};
diff --git a/libio/tst_swprintf.c b/libio/tst_swprintf.c
index 1f997b9..169951d 100644
--- a/libio/tst_swprintf.c
+++ b/libio/tst_swprintf.c
@@ -1,4 +1,5 @@
#include <array_length.h>
+#include <errno.h>
#include <stdio.h>
#include <support/check.h>
#include <sys/types.h>
@@ -37,6 +38,8 @@ do_test (void)
for (n = 0; n < array_length (tests); ++n)
{
+ wmemset (buf, 0xabcd, array_length (buf));
+ errno = 0;
ssize_t res = swprintf (buf, tests[n].n, L"%s", tests[n].str);
if (tests[n].exp < 0 && res >= 0)
@@ -52,9 +55,31 @@ do_test (void)
swprintf (buf, %zu, L\"%%s\", \"%s\") expected to return %zd, but got %zd\n",
tests[n].n, tests[n].str, tests[n].exp, res);
}
- else
- printf ("swprintf (buf, %zu, L\"%%s\", \"%s\") OK\n",
- tests[n].n, tests[n].str);
+ else if (res < 0
+ && tests[n].n > 0
+ && wcsnlen (buf, array_length (buf)) == array_length (buf))
+ {
+ support_record_failure ();
+ printf ("\
+error: swprintf (buf, %zu, L\"%%s\", \"%s\") missing null terminator\n",
+ tests[n].n, tests[n].str);
+ }
+ else if (res < 0
+ && tests[n].n > 0
+ && wcsnlen (buf, array_length (buf)) < array_length (buf)
+ && buf[wcsnlen (buf, array_length (buf)) + 1] != 0xabcd)
+ {
+ support_record_failure ();
+ printf ("\
+error: swprintf (buf, %zu, L\"%%s\", \"%s\") out of bounds write\n",
+ tests[n].n, tests[n].str);
+ }
+
+ if (res < 0 && tests[n].n < 0)
+ TEST_COMPARE (errno, E2BIG);
+
+ printf ("swprintf (buf, %zu, L\"%%s\", \"%s\") OK\n",
+ tests[n].n, tests[n].str);
}
TEST_COMPARE (swprintf (buf, array_length (buf), L"%.0s", "foo"), 0);
diff --git a/libio/vswprintf.c b/libio/vswprintf.c
index 5a9ccdf..f53545c 100644
--- a/libio/vswprintf.c
+++ b/libio/vswprintf.c
@@ -24,101 +24,37 @@
This exception applies to code released by its copyright holders
in files containing the exception. */
-#include "libioP.h"
-#include "strfile.h"
-
-
-static wint_t _IO_wstrn_overflow (FILE *fp, wint_t c) __THROW;
-
-static wint_t
-_IO_wstrn_overflow (FILE *fp, wint_t c)
-{
- /* When we come to here this means the user supplied buffer is
- filled. But since we must return the number of characters which
- would have been written in total we must provide a buffer for
- further use. We can do this by writing on and on in the overflow
- buffer in the _IO_wstrnfile structure. */
- _IO_wstrnfile *snf = (_IO_wstrnfile *) fp;
-
- if (fp->_wide_data->_IO_buf_base != snf->overflow_buf)
- {
- _IO_wsetb (fp, snf->overflow_buf,
- snf->overflow_buf + (sizeof (snf->overflow_buf)
- / sizeof (wchar_t)), 0);
-
- fp->_wide_data->_IO_write_base = snf->overflow_buf;
- fp->_wide_data->_IO_read_base = snf->overflow_buf;
- fp->_wide_data->_IO_read_ptr = snf->overflow_buf;
- fp->_wide_data->_IO_read_end = (snf->overflow_buf
- + (sizeof (snf->overflow_buf)
- / sizeof (wchar_t)));
- }
-
- fp->_wide_data->_IO_write_ptr = snf->overflow_buf;
- fp->_wide_data->_IO_write_end = snf->overflow_buf;
-
- /* Since we are not really interested in storing the characters
- which do not fit in the buffer we simply ignore it. */
- return c;
-}
-
-
-const struct _IO_jump_t _IO_wstrn_jumps libio_vtable attribute_hidden =
-{
- JUMP_INIT_DUMMY,
- JUMP_INIT(finish, _IO_wstr_finish),
- JUMP_INIT(overflow, (_IO_overflow_t) _IO_wstrn_overflow),
- JUMP_INIT(underflow, (_IO_underflow_t) _IO_wstr_underflow),
- JUMP_INIT(uflow, (_IO_underflow_t) _IO_wdefault_uflow),
- JUMP_INIT(pbackfail, (_IO_pbackfail_t) _IO_wstr_pbackfail),
- JUMP_INIT(xsputn, _IO_wdefault_xsputn),
- JUMP_INIT(xsgetn, _IO_wdefault_xsgetn),
- JUMP_INIT(seekoff, _IO_wstr_seekoff),
- JUMP_INIT(seekpos, _IO_default_seekpos),
- JUMP_INIT(setbuf, _IO_default_setbuf),
- JUMP_INIT(sync, _IO_default_sync),
- JUMP_INIT(doallocate, _IO_wdefault_doallocate),
- JUMP_INIT(read, _IO_default_read),
- JUMP_INIT(write, _IO_default_write),
- JUMP_INIT(seek, _IO_default_seek),
- JUMP_INIT(close, _IO_default_close),
- JUMP_INIT(stat, _IO_default_stat),
- JUMP_INIT(showmanyc, _IO_default_showmanyc),
- JUMP_INIT(imbue, _IO_default_imbue)
-};
-
+#include <errno.h>
+#include <math_ldbl_opt.h>
+#include <printf.h>
+#include <printf_buffer.h>
int
__vswprintf_internal (wchar_t *string, size_t maxlen, const wchar_t *format,
va_list args, unsigned int mode_flags)
{
- _IO_wstrnfile sf;
- int ret;
- struct _IO_wide_data wd;
-#ifdef _IO_MTSAFE_IO
- sf.f._sbf._f._lock = NULL;
-#endif
-
if (maxlen == 0)
/* Since we have to write at least the terminating L'\0' a buffer
length of zero always makes the function fail. */
return -1;
- _IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, 0, &wd, &_IO_wstrn_jumps);
- _IO_fwide (&sf.f._sbf._f, 1);
- string[0] = L'\0';
- _IO_wstr_init_static (&sf.f._sbf._f, string, maxlen - 1, string);
- ret = __vfwprintf_internal ((FILE *) &sf.f._sbf, format, args, mode_flags);
+ struct __wprintf_buffer buf;
+ __wprintf_buffer_init (&buf, string, maxlen, __wprintf_buffer_mode_swprintf);
- if (sf.f._sbf._f._wide_data->_IO_buf_base == sf.overflow_buf)
- /* ISO C99 requires swprintf/vswprintf to return an error if the
- output does not fit in the provided buffer. */
- return -1;
+ __wprintf_buffer (&buf, format, args, mode_flags);
+
+ if (buf.write_ptr == buf.write_end)
+ {
+ /* Buffer has been filled exactly, excluding the null wide
+ character. This is an error because the null wide character
+ is required. */
+ buf.write_end[-1] = L'\0';
+ return -1;
+ }
- /* Terminate the string. */
- *sf.f._sbf._f._wide_data->_IO_write_ptr = '\0';
+ buf.write_ptr[0] = L'\0';
- return ret;
+ return __wprintf_buffer_done (&buf);
}
int
diff --git a/manual/stdio.texi b/manual/stdio.texi
index 4aa1a2b..f6319a4 100644
--- a/manual/stdio.texi
+++ b/manual/stdio.texi
@@ -2412,9 +2412,10 @@ allocate at least @var{size} wide characters for the string @var{ws}.
The return value is the number of characters generated for the given
input, excluding the trailing null. If not all output fits into the
-provided buffer a negative value is returned. You should try again with
-a bigger output string. @emph{Note:} this is different from how
-@code{snprintf} handles this situation.
+provided buffer a negative value is returned, and @code{errno} is set to
+@code{E2BIG}. (The setting of @code{errno} is a GNU extension.) You
+should try again with a bigger output string. @emph{Note:} this is
+different from how @code{snprintf} handles this situation.
Note that the corresponding narrow stream function takes fewer
parameters. @code{swprintf} in fact corresponds to the @code{snprintf}
diff --git a/stdio-common/wprintf_buffer_flush.c b/stdio-common/wprintf_buffer_flush.c
index 2d91095..46af0f3 100644
--- a/stdio-common/wprintf_buffer_flush.c
+++ b/stdio-common/wprintf_buffer_flush.c
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
+#include <errno.h>
#include <printf_buffer.h>
#include "printf_buffer-wchar_t.h"
@@ -31,6 +32,11 @@ __wprintf_buffer_do_flush (struct __wprintf_buffer *buf)
case __wprintf_buffer_mode_to_file:
__wprintf_buffer_flush_to_file ((struct __wprintf_buffer_to_file *) buf);
return;
+ case __wprintf_buffer_mode_swprintf:
+ buf->write_end[-1] = L'\0';
+ __set_errno (E2BIG);
+ __wprintf_buffer_mark_failed (buf);
+ return;
}
__builtin_trap ();
}