diff options
| -rw-r--r-- | ChangeLog | 9 | ||||
| -rw-r--r-- | NEWS | 8 | ||||
| -rw-r--r-- | malloc/malloc.c | 23 | ||||
| -rw-r--r-- | manual/memory.texi | 20 | ||||
| -rw-r--r-- | manual/tunables.texi | 28 |
5 files changed, 37 insertions, 51 deletions
@@ -1,5 +1,14 @@ 2017-08-30 Florian Weimer <fweimer@redhat.com> + [BZ #21754] + * malloc/malloc.c (malloc_printerr): Always terminate the process, + without printing a backtrace. Do not leak any information in the + error message. + * manual/memory.texi (Heap Consistency Checking): Update. + * manual/tunables.texi (Memory Allocation Tunables): Likewise. + +2017-08-30 Florian Weimer <fweimer@redhat.com> + Do not scale NPTL tests with available number of CPUs. * nptl/tst-cond16.c (count): Set to constant value of 8. * nptl/tst-cond18.c (count): Likewise. @@ -12,6 +12,14 @@ Major new features: * Optimized x86-64 asin, atan2, exp, expf, log, pow, atan, sin and tan with FMA, contributed by Arjan van de Ven and H.J. Lu from Intel. +* In order to support faster and safer process termination the malloc API + family of functions will no longer print a failure address and stack + backtrace after detecting heap corruption. The goal is to minimize the + amount of work done after corruption is detected and to avoid potential + security issues in continued process execution. Reducing shutdown time + leads to lower overall process restart latency, so there is benefit both + from a security and performance perspective. + Deprecated and removed features, and other changes affecting compatibility: * On GNU/Linux, the obsolete Linux constant PTRACE_SEIZE_DEVEL is no longer diff --git a/malloc/malloc.c b/malloc/malloc.c index e3ff778..d290fde 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1019,7 +1019,8 @@ static void* _int_realloc(mstate, mchunkptr, INTERNAL_SIZE_T, static void* _int_memalign(mstate, size_t, size_t); static void* _mid_memalign(size_t, size_t, void *); -static void malloc_printerr(int action, const char *str, void *ptr, mstate av); +static void malloc_printerr(int action, const char *str, void *ptr, mstate av) + __attribute__ ((noreturn)); static void* internal_function mem2mem_check(void *p, size_t sz); static int internal_function top_check(void); @@ -5408,24 +5409,8 @@ malloc_printerr (int action, const char *str, void *ptr, mstate ar_ptr) if (ar_ptr) set_arena_corrupt (ar_ptr); - if ((action & 5) == 5) - __libc_message ((action & 2) ? (do_abort | do_backtrace) : do_message, - "%s\n", str); - else if (action & 1) - { - char buf[2 * sizeof (uintptr_t) + 1]; - - buf[sizeof (buf) - 1] = '\0'; - char *cp = _itoa_word ((uintptr_t) ptr, &buf[sizeof (buf) - 1], 16, 0); - while (cp > buf) - *--cp = '0'; - - __libc_message ((action & 2) ? (do_abort | do_backtrace) : do_message, - "*** Error in `%s': %s: 0x%s ***\n", - __libc_argv[0] ? : "<unknown>", str, cp); - } - else if (action & 2) - abort (); + __libc_message (do_abort, "%s\n", str); + __builtin_unreachable (); } /* We need a wrapper function for one of the additions of POSIX. */ diff --git a/manual/memory.texi b/manual/memory.texi index 82f4738..13cce7a 100644 --- a/manual/memory.texi +++ b/manual/memory.texi @@ -1309,17 +1309,15 @@ The block was already freed. Another possibility to check for and guard against bugs in the use of @code{malloc}, @code{realloc} and @code{free} is to set the environment -variable @code{MALLOC_CHECK_}. When @code{MALLOC_CHECK_} is set, a -special (less efficient) implementation is used which is designed to be -tolerant against simple errors, such as double calls of @code{free} with -the same argument, or overruns of a single byte (off-by-one bugs). Not -all such errors can be protected against, however, and memory leaks can -result. If @code{MALLOC_CHECK_} is set to @code{0}, any detected heap -corruption is silently ignored; if set to @code{1}, a diagnostic is -printed on @code{stderr}; if set to @code{2}, @code{abort} is called -immediately. This can be useful because otherwise a crash may happen -much later, and the true cause for the problem is then very hard to -track down. +variable @code{MALLOC_CHECK_}. When @code{MALLOC_CHECK_} is set to a +non-zero value, a special (less efficient) implementation is used which +is designed to be tolerant against simple errors, such as double calls +of @code{free} with the same argument, or overruns of a single byte +(off-by-one bugs). Not all such errors can be protected against, +however, and memory leaks can result. + +Any detected heap corruption results in immediate termination of the +process. There is one problem with @code{MALLOC_CHECK_}: in SUID or SGID binaries it could possibly be exploited since diverging from the normal programs diff --git a/manual/tunables.texi b/manual/tunables.texi index 3c19567..b09e3fe 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -71,27 +71,13 @@ following tunables in the @code{malloc} namespace: This tunable supersedes the @env{MALLOC_CHECK_} environment variable and is identical in features. -Setting this tunable enables a special (less efficient) memory allocator for -the malloc family of functions that is designed to be tolerant against simple -errors such as double calls of free with the same argument, or overruns of a -single byte (off-by-one bugs). Not all such errors can be protected against, -however, and memory leaks can result. The following list describes the values -that this tunable can take and the effect they have on malloc functionality: - -@itemize @bullet -@item @code{0} Ignore all errors. The default allocator continues to be in -use, but all errors are silently ignored. -@item @code{1} Report errors. The alternate allocator is selected and heap -corruption, if detected, is reported as diagnostic messages to @code{stderr} -and the program continues execution. -@item @code{2} Abort on errors. The alternate allocator is selected and if -heap corruption is detected, the program is ended immediately by calling -@code{abort}. -@item @code{3} Fully enabled. The alternate allocator is selected and is fully -functional. That is, if heap corruption is detected, a verbose diagnostic -message is printed to @code{stderr} and the program is ended by calling -@code{abort}. -@end itemize +Setting this tunable to a non-zero value enables a special (less +efficient) memory allocator for the malloc family of functions that is +designed to be tolerant against simple errors such as double calls of +free with the same argument, or overruns of a single byte (off-by-one +bugs). Not all such errors can be protected against, however, and memory +leaks can result. Any detected heap corruption results in immediate +termination of the process. Like @env{MALLOC_CHECK_}, @code{glibc.malloc.check} has a problem in that it diverges from normal program behavior by writing to @code{stderr}, which could |