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From: Szabolcs Nagy <nsz@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/arm/morello/main] malloc: Don't use __libc_free for tcache cleanup Date: Wed, 23 Nov 2022 14:50:17 +0000 (GMT) [thread overview] Message-ID: <20221123145017.7C9783852C61@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=32c64139eef90920af88e85c07c168fcada73935 commit 32c64139eef90920af88e85c07c168fcada73935 Author: Szabolcs Nagy <szabolcs.nagy@arm.com> Date: Mon Oct 3 11:58:09 2022 +0100 malloc: Don't use __libc_free for tcache cleanup __libc_free must only be used for memory given out by __libc_malloc and similar public apis, but tcache stores a cache of already freed pointers and itself is allocated using internal malloc apis. Strong double free detection in __libc_free breaks tcache_thread_shutdown, so use a cut down version of free to reset tcache entries. Diff: --- malloc/malloc.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/malloc/malloc.c b/malloc/malloc.c index 701adbebca..7ada0e5ae0 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -3205,6 +3205,35 @@ tcache_get (size_t tc_idx) return (void *) e; } +/* Cut down __libc_free for cleaning up tcache entries. */ +static void +tcache_libc_free (void *mem) +{ + int err = errno; + mchunkptr p = mem2chunk(mem); + if (chunk_is_mmapped (p)) + { + /* See if the dynamic brk/mmap threshold needs adjusting. + Dumped fake mmapped chunks do not affect the threshold. */ + if (!mp_.no_dyn_threshold + && chunksize_nomask (p) > mp_.mmap_threshold + && chunksize_nomask (p) <= DEFAULT_MMAP_THRESHOLD_MAX) + { + mp_.mmap_threshold = chunksize (p); + mp_.trim_threshold = 2 * mp_.mmap_threshold; + LIBC_PROBE (memory_mallopt_free_dyn_thresholds, 2, + mp_.mmap_threshold, mp_.trim_threshold); + } + munmap_chunk (p); + } + else + { + mstate ar_ptr = arena_for_chunk (p); + _int_free (ar_ptr, p, 0); + } + __set_errno (err); +} + static void tcache_thread_shutdown (void) { @@ -3230,11 +3259,11 @@ tcache_thread_shutdown (void) malloc_printerr ("tcache_thread_shutdown(): " "unaligned tcache chunk detected"); tcache_tmp->entries[i] = REVEAL_PTR (e->next); - __libc_free (e); + tcache_libc_free (e); } } - __libc_free (tcache_tmp); + tcache_libc_free (tcache_tmp); } static void
next reply other threads:[~2022-11-23 14:50 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-23 14:50 Szabolcs Nagy [this message] -- strict thread matches above, loose matches on Subject: below -- 2022-10-27 14:00 Szabolcs Nagy 2022-10-26 15:21 Szabolcs Nagy 2022-10-12 14:18 Szabolcs Nagy
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