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glibc.8004
Avoid-deadlock-in-malloc-on-backtrace-BZ-16159....
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File Avoid-deadlock-in-malloc-on-backtrace-BZ-16159.patch of Package glibc.8004
2015-05-19 Siddhesh Poyarekar <siddhesh@redhat.com> [BZ #16159] * malloc/Makefile (tests): New test case tst-malloc-backtrace. * malloc/arena.c (arena_lock): Check if arena is corrupt. (reused_arena): Find a non-corrupt arena. (heap_trim): Pass arena to unlink. * malloc/hooks.c (malloc_check_get_size): Pass arena to malloc_printerr. (top_check): Likewise. (free_check): Likewise. (realloc_check): Likewise. * malloc/malloc.c (malloc_printerr): Add arena argument. (unlink): Likewise. (munmap_chunk): Adjust. (ARENA_CORRUPTION_BIT): New macro. (arena_is_corrupt): Likewise. (set_arena_corrupt): Likewise. (sysmalloc): Use mmap if there are no usable arenas. (_int_malloc): Likewise. (__libc_malloc): Don't fail if arena_get returns NULL. (_mid_memalign): Likewise. (__libc_calloc): Likewise. (__libc_realloc): Adjust for additional argument to malloc_printerr. (_int_free): Likewise. (malloc_consolidate): Likewise. (_int_realloc): Likewise. (_int_memalign): Don't touch corrupt arenas. * malloc/tst-malloc-backtrace.c: New test case. Index: glibc-2.19/malloc/Makefile =================================================================== --- glibc-2.19.orig/malloc/Makefile +++ glibc-2.19/malloc/Makefile @@ -27,7 +27,8 @@ headers := $(dist-headers) obstack.h mch tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \ tst-mallocstate tst-mcheck tst-mallocfork tst-trim1 \ tst-malloc-usable tst-realloc tst-posix_memalign \ - tst-pvalloc tst-memalign + tst-pvalloc tst-memalign \ + tst-malloc-backtrace test-srcs = tst-mtrace routines = malloc morecore mcheck mtrace obstack @@ -146,3 +147,6 @@ $(objpfx)libmemusage.so: $(common-objpfx # Extra dependencies $(foreach o,$(all-object-suffixes),$(objpfx)malloc$(o)): arena.c hooks.c + +$(objpfx)tst-malloc-backtrace: $(common-objpfx)nptl/libpthread.so \ + $(common-objpfx)nptl/libpthread_nonshared.a Index: glibc-2.19/malloc/arena.c =================================================================== --- glibc-2.19.orig/malloc/arena.c +++ glibc-2.19/malloc/arena.c @@ -114,7 +114,7 @@ int __malloc_initialized = -1; } while (0) #define arena_lock(ptr, size) do { \ - if (ptr) \ + if (ptr && !arena_is_corrupt (ptr)) \ (void) mutex_lock (&ptr->mutex); \ else \ ptr = arena_get2 (ptr, (size), NULL); \ @@ -702,7 +702,7 @@ heap_trim (heap_info *heap, size_t pad) if (!prev_inuse (p)) /* consolidate backward */ { p = prev_chunk (p); - unlink (p, bck, fwd); + unlink (ar_ptr, p, bck, fwd); } assert (((unsigned long) ((char *) p + new_size) & (pagesz - 1)) == 0); assert (((char *) p + new_size) == ((char *) heap + heap->size)); @@ -828,7 +828,7 @@ reused_arena (mstate avoid_arena) result = next_to_use; do { - if (!mutex_trylock (&result->mutex)) + if (!arena_is_corrupt (result) && !mutex_trylock (&result->mutex)) goto out; result = result->next; @@ -840,7 +840,21 @@ reused_arena (mstate avoid_arena) if (result == avoid_arena) result = result->next; - /* No arena available. Wait for the next in line. */ + /* Make sure that the arena we get is not corrupted. */ + mstate begin = result; + while (arena_is_corrupt (result) || result == avoid_arena) + { + result = result->next; + if (result == begin) + break; + } + + /* We could not find any arena that was either not corrupted or not the one + we wanted to avoid. */ + if (result == begin || result == avoid_arena) + return NULL; + + /* No arena available without contention. Wait for the next in line. */ LIBC_PROBE (memory_arena_reuse_wait, 3, &result->mutex, result, avoid_arena); (void) mutex_lock (&result->mutex); Index: glibc-2.19/malloc/hooks.c =================================================================== --- glibc-2.19.orig/malloc/hooks.c +++ glibc-2.19/malloc/hooks.c @@ -112,7 +112,8 @@ malloc_check_get_size (mchunkptr p) if (c <= 0 || size < (c + 2 * SIZE_SZ)) { malloc_printerr (check_action, "malloc_check_get_size: memory corruption", - chunk2mem (p)); + chunk2mem (p), + chunk_is_mmapped (p) ? NULL : arena_for_chunk (p)); return 0; } } @@ -237,7 +238,8 @@ top_check (void) (char *) t + chunksize (t) == mp_.sbrk_base + main_arena.system_mem))) return 0; - malloc_printerr (check_action, "malloc: top chunk is corrupt", t); + malloc_printerr (check_action, "malloc: top chunk is corrupt", t, + &main_arena); /* Try to set up a new top chunk. */ brk = MORECORE (0); @@ -295,7 +297,8 @@ free_check (void *mem, const void *calle { (void) mutex_unlock (&main_arena.mutex); - malloc_printerr (check_action, "free(): invalid pointer", mem); + malloc_printerr (check_action, "free(): invalid pointer", mem, + &main_arena); return; } if (chunk_is_mmapped (p)) @@ -333,7 +336,8 @@ realloc_check (void *oldmem, size_t byte (void) mutex_unlock (&main_arena.mutex); if (!oldp) { - malloc_printerr (check_action, "realloc(): invalid pointer", oldmem); + malloc_printerr (check_action, "realloc(): invalid pointer", oldmem, + &main_arena); return malloc_check (bytes, NULL); } const INTERNAL_SIZE_T oldsize = chunksize (oldp); Index: glibc-2.19/malloc/malloc.c =================================================================== --- glibc-2.19.orig/malloc/malloc.c +++ glibc-2.19/malloc/malloc.c @@ -1054,7 +1054,7 @@ static void* _int_realloc(mstate, mchun 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); +static void malloc_printerr(int action, const char *str, void *ptr, mstate av); static void* internal_function mem2mem_check(void *p, size_t sz); static int internal_function top_check(void); @@ -1406,11 +1406,11 @@ typedef struct malloc_chunk *mbinptr; #define last(b) ((b)->bk) /* Take a chunk off a bin list */ -#define unlink(P, BK, FD) { \ +#define unlink(AV, P, BK, FD) { \ FD = P->fd; \ BK = P->bk; \ if (__builtin_expect (FD->bk != P || BK->fd != P, 0)) \ - malloc_printerr (check_action, "corrupted double-linked list", P); \ + malloc_printerr (check_action, "corrupted double-linked list", P, AV); \ else { \ FD->bk = BK; \ BK->fd = FD; \ @@ -1649,6 +1649,15 @@ typedef struct malloc_chunk *mfastbinptr #define set_noncontiguous(M) ((M)->flags |= NONCONTIGUOUS_BIT) #define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT) +/* ARENA_CORRUPTION_BIT is set if a memory corruption was detected on the + arena. Such an arena is no longer used to allocate chunks. Chunks + allocated in that arena before detecting corruption are not freed. */ + +#define ARENA_CORRUPTION_BIT (4U) + +#define arena_is_corrupt(A) (((A)->flags & ARENA_CORRUPTION_BIT)) +#define set_arena_corrupt(A) ((A)->flags |= ARENA_CORRUPTION_BIT) + /* Set value of max_fast. Use impossibly small value if 0. @@ -2278,8 +2287,9 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av rather than expanding top. */ - if ((unsigned long) (nb) >= (unsigned long) (mp_.mmap_threshold) && - (mp_.n_mmaps < mp_.n_mmaps_max)) + if (av == NULL + || ((unsigned long) (nb) >= (unsigned long) (mp_.mmap_threshold) + && (mp_.n_mmaps < mp_.n_mmaps_max))) { char *mm; /* return value from mmap call*/ @@ -2352,6 +2362,10 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av } } + /* There are no usable arenas and mmap also failed. */ + if (av == NULL) + return 0; + /* Record incoming configuration of top */ old_top = av->top; @@ -2526,7 +2540,8 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av else if (contiguous (av) && old_size && brk < old_end) { /* Oops! Someone else killed our space.. Can't touch anything. */ - malloc_printerr (3, "break adjusted to free malloc space", brk); + malloc_printerr (3, "break adjusted to free malloc space", brk, + av); } /* @@ -2813,7 +2828,7 @@ munmap_chunk (mchunkptr p) if (__builtin_expect (((block | total_size) & (GLRO (dl_pagesize) - 1)) != 0, 0)) { malloc_printerr (check_action, "munmap_chunk(): invalid pointer", - chunk2mem (p)); + chunk2mem (p), NULL); return; } @@ -2883,22 +2898,19 @@ __libc_malloc (size_t bytes) arena_get (ar_ptr, bytes); - if (!ar_ptr) - return 0; - victim = _int_malloc (ar_ptr, bytes); - if (!victim) + /* Retry with another arena only if we were able to find a usable arena + before. */ + if (!victim && ar_ptr != NULL) { LIBC_PROBE (memory_malloc_retry, 1, bytes); ar_ptr = arena_get_retry (ar_ptr, bytes); - if (__builtin_expect (ar_ptr != NULL, 1)) - { - victim = _int_malloc (ar_ptr, bytes); - (void) mutex_unlock (&ar_ptr->mutex); - } + victim = _int_malloc (ar_ptr, bytes); } - else + + if (ar_ptr != NULL) (void) mutex_unlock (&ar_ptr->mutex); + assert (!victim || chunk_is_mmapped (mem2chunk (victim)) || ar_ptr == arena_for_chunk (mem2chunk (victim))); return victim; @@ -2974,6 +2986,11 @@ __libc_realloc (void *oldmem, size_t byt /* its size */ const INTERNAL_SIZE_T oldsize = chunksize (oldp); + if (chunk_is_mmapped (oldp)) + ar_ptr = NULL; + else + ar_ptr = arena_for_chunk (oldp); + /* Little security check which won't hurt performance: the allocator never wrapps around at the end of the address space. Therefore we can exclude some size values which might appear @@ -2981,7 +2998,8 @@ __libc_realloc (void *oldmem, size_t byt if (__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, 0) || __builtin_expect (misaligned_chunk (oldp), 0)) { - malloc_printerr (check_action, "realloc(): invalid pointer", oldmem); + malloc_printerr (check_action, "realloc(): invalid pointer", oldmem, + ar_ptr); return NULL; } @@ -3010,7 +3028,6 @@ __libc_realloc (void *oldmem, size_t byt return newmem; } - ar_ptr = arena_for_chunk (oldp); #if THREAD_STATS if (!mutex_trylock (&ar_ptr->mutex)) ++(ar_ptr->stat_lock_direct); @@ -3023,7 +3040,6 @@ __libc_realloc (void *oldmem, size_t byt (void) mutex_lock (&ar_ptr->mutex); #endif - newp = _int_realloc (ar_ptr, oldp, oldsize, nb); (void) mutex_unlock (&ar_ptr->mutex); @@ -3098,22 +3114,18 @@ _mid_memalign (size_t alignment, size_t } arena_get (ar_ptr, bytes + alignment + MINSIZE); - if (!ar_ptr) - return 0; p = _int_memalign (ar_ptr, alignment, bytes); - if (!p) + if (!p && ar_ptr != NULL) { LIBC_PROBE (memory_memalign_retry, 2, bytes, alignment); ar_ptr = arena_get_retry (ar_ptr, bytes); - if (__builtin_expect (ar_ptr != NULL, 1)) - { - p = _int_memalign (ar_ptr, alignment, bytes); - (void) mutex_unlock (&ar_ptr->mutex); - } + p = _int_memalign (ar_ptr, alignment, bytes); } - else + + if (ar_ptr != NULL) (void) mutex_unlock (&ar_ptr->mutex); + assert (!p || chunk_is_mmapped (mem2chunk (p)) || ar_ptr == arena_for_chunk (mem2chunk (p))); return p; @@ -3193,47 +3205,53 @@ __libc_calloc (size_t n, size_t elem_siz sz = bytes; arena_get (av, sz); - if (!av) - return 0; - - /* Check if we hand out the top chunk, in which case there may be no - need to clear. */ + if (av) + { + /* Check if we hand out the top chunk, in which case there may be no + need to clear. */ #if MORECORE_CLEARS - oldtop = top (av); - oldtopsize = chunksize (top (av)); + oldtop = top (av); + oldtopsize = chunksize (top (av)); # if MORECORE_CLEARS < 2 - /* Only newly allocated memory is guaranteed to be cleared. */ - if (av == &main_arena && - oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *) oldtop) - oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *) oldtop); + /* Only newly allocated memory is guaranteed to be cleared. */ + if (av == &main_arena && + oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *) oldtop) + oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *) oldtop); # endif - if (av != &main_arena) + if (av != &main_arena) + { + heap_info *heap = heap_for_ptr (oldtop); + if (oldtopsize < (char *) heap + heap->mprotect_size - (char *) oldtop) + oldtopsize = (char *) heap + heap->mprotect_size - (char *) oldtop; + } +#endif + } + else { - heap_info *heap = heap_for_ptr (oldtop); - if (oldtopsize < (char *) heap + heap->mprotect_size - (char *) oldtop) - oldtopsize = (char *) heap + heap->mprotect_size - (char *) oldtop; + /* No usable arenas. */ + oldtop = 0; + oldtopsize = 0; } -#endif mem = _int_malloc (av, sz); assert (!mem || chunk_is_mmapped (mem2chunk (mem)) || av == arena_for_chunk (mem2chunk (mem))); - if (mem == 0) + if (mem == 0 && av != NULL) { LIBC_PROBE (memory_calloc_retry, 1, sz); av = arena_get_retry (av, sz); - if (__builtin_expect (av != NULL, 1)) - { - mem = _int_malloc (av, sz); - (void) mutex_unlock (&av->mutex); - } - if (mem == 0) - return 0; + mem = _int_malloc (av, sz); } - else + + if (av != NULL) (void) mutex_unlock (&av->mutex); + + /* Allocation failed even after a retry. */ + if (mem == 0) + return 0; + p = mem2chunk (mem); /* Two optional cases in which clearing not necessary */ @@ -3329,6 +3347,16 @@ _int_malloc (mstate av, size_t bytes) checked_request2size (bytes, nb); + /* There are no usable arenas. Fall back to sysmalloc to get a chunk from + mmap. */ + if (__glibc_unlikely (av == NULL)) + { + void *p = sysmalloc (nb, av); + if (p != NULL) + alloc_perturb (p, bytes); + return p; + } + /* If the size qualifies as a fastbin, first check corresponding bin. This code is safe to execute even if av is not yet initialized, so we @@ -3354,7 +3382,7 @@ _int_malloc (mstate av, size_t bytes) { errstr = "malloc(): memory corruption (fast)"; errout: - malloc_printerr (check_action, errstr, chunk2mem (victim)); + malloc_printerr (check_action, errstr, chunk2mem (victim), av); return NULL; } check_remalloced_chunk (av, victim, nb); @@ -3443,7 +3471,7 @@ _int_malloc (mstate av, size_t bytes) if (__builtin_expect (victim->size <= 2 * SIZE_SZ, 0) || __builtin_expect (victim->size > av->system_mem, 0)) malloc_printerr (check_action, "malloc(): memory corruption", - chunk2mem (victim)); + chunk2mem (victim), av); size = chunksize (victim); /* @@ -3590,7 +3618,7 @@ _int_malloc (mstate av, size_t bytes) victim = victim->fd; remainder_size = size - nb; - unlink (victim, bck, fwd); + unlink (av, victim, bck, fwd); /* Exhaust */ if (remainder_size < MINSIZE) @@ -3695,7 +3723,7 @@ _int_malloc (mstate av, size_t bytes) remainder_size = size - nb; /* unlink */ - unlink (victim, bck, fwd); + unlink (av, victim, bck, fwd); /* Exhaust */ if (remainder_size < MINSIZE) @@ -3835,7 +3863,7 @@ _int_free (mstate av, mchunkptr p, int h errout: if (!have_lock && locked) (void) mutex_unlock (&av->mutex); - malloc_printerr (check_action, errstr, chunk2mem (p)); + malloc_printerr (check_action, errstr, chunk2mem (p), av); return; } /* We know that each chunk is at least MINSIZE bytes in size or a @@ -3982,7 +4010,7 @@ _int_free (mstate av, mchunkptr p, int h prevsize = p->prev_size; size += prevsize; p = chunk_at_offset(p, -((long) prevsize)); - unlink(p, bck, fwd); + unlink(av, p, bck, fwd); } if (nextchunk != av->top) { @@ -3991,7 +4019,7 @@ _int_free (mstate av, mchunkptr p, int h /* consolidate forward */ if (!nextinuse) { - unlink(nextchunk, bck, fwd); + unlink(av, nextchunk, bck, fwd); size += nextsize; } else clear_inuse_bit_at_offset(nextchunk, 0); @@ -4152,7 +4180,7 @@ static void malloc_consolidate(mstate av prevsize = p->prev_size; size += prevsize; p = chunk_at_offset(p, -((long) prevsize)); - unlink(p, bck, fwd); + unlink(av, p, bck, fwd); } if (nextchunk != av->top) { @@ -4160,7 +4188,7 @@ static void malloc_consolidate(mstate av if (!nextinuse) { size += nextsize; - unlink(nextchunk, bck, fwd); + unlink(av, nextchunk, bck, fwd); } else clear_inuse_bit_at_offset(nextchunk, 0); @@ -4229,7 +4257,7 @@ _int_realloc(mstate av, mchunkptr oldp, { errstr = "realloc(): invalid old size"; errout: - malloc_printerr (check_action, errstr, chunk2mem (oldp)); + malloc_printerr (check_action, errstr, chunk2mem (oldp), av); return NULL; } @@ -4275,7 +4303,7 @@ _int_realloc(mstate av, mchunkptr oldp, (unsigned long) (nb)) { newp = oldp; - unlink (next, bck, fwd); + unlink (av, next, bck, fwd); } /* allocate, copy, free */ @@ -4470,6 +4498,10 @@ _int_memalign (mstate av, size_t alignme static int mtrim (mstate av, size_t pad) { + /* Don't touch corrupt arenas. */ + if (arena_is_corrupt (av)) + return 0; + /* Ensure initialization/consolidation */ malloc_consolidate (av); @@ -4976,8 +5008,14 @@ libc_hidden_def (__libc_mallopt) extern char **__libc_argv attribute_hidden; static void -malloc_printerr (int action, const char *str, void *ptr) +malloc_printerr (int action, const char *str, void *ptr, mstate ar_ptr) { + /* Avoid using this arena in future. We do not attempt to synchronize this + with anything else because we minimally want to ensure that __libc_message + gets its resources safely without stumbling on the current corruption. */ + if (ar_ptr) + set_arena_corrupt (ar_ptr); + if ((action & 5) == 5) __libc_message (action & 2, "%s\n", str); else if (action & 1) Index: glibc-2.19/malloc/tst-malloc-backtrace.c =================================================================== --- /dev/null +++ glibc-2.19/malloc/tst-malloc-backtrace.c @@ -0,0 +1,50 @@ +/* Verify that backtrace does not deadlock on itself on memory corruption. + Copyright (C) 2015 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 <stdlib.h> + +#define SIZE 4096 + +/* Wrap free with a function to prevent gcc from optimizing it out. */ +static void +__attribute__((noinline)) +call_free (void *ptr) +{ + free (ptr); + *(size_t *)(ptr - sizeof (size_t)) = 1; +} + +int +do_test (void) +{ + void *ptr1 = malloc (SIZE); + void *ptr2 = malloc (SIZE); + + call_free (ptr1); + ptr1 = malloc (SIZE); + + /* Not reached. The return statement is to put ptr2 into use so that gcc + doesn't optimize out that malloc call. */ + return (ptr1 == ptr2); +} + +#define TEST_FUNCTION do_test () +#define EXPECTED_SIGNAL SIGABRT + +#include "../test-skeleton.c"
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