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Guard use of sdallocx with BORINGSSL_SDALLOCX

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See comment in change and https://github.com/grpc/grpc/issues/25450

Update-note: consumers may wish to define BORINGSSL_SDALLOCX if using
tcmalloc.

Change-Id: I123fe31a6c4013f1ce0c056f82a316c71df84939
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48885
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
This commit is contained in:
Adam Langley 2021-08-13 10:21:29 -07:00 committed by Boringssl LUCI CQ
parent a603c828dc
commit 80df7398ce
1 changed files with 16 additions and 12 deletions
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28
crypto/mem.c
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@ -93,15 +93,19 @@ static void __asan_unpoison_memory_region(const void *addr, size_t size) {}
#define WEAK_SYMBOL_FUNC(rettype, name, args) static rettype(*name) args = NULL;
#endif
#if defined(BORINGSSL_SDALLOCX)
// sdallocx is a sized |free| function. By passing the size (which we happen to
// always know in BoringSSL), the malloc implementation can save work. We cannot
// depend on |sdallocx| being available, however, so it's a weak symbol.
// always know in BoringSSL), the malloc implementation can save work.
//
// This will always be safe, but will only be overridden if the malloc
// implementation is statically linked with BoringSSL. So, if |sdallocx| is
// provided in, say, libc.so, we still won't use it because that's dynamically
// linked. This isn't an ideal result, but its helps in some cases.
WEAK_SYMBOL_FUNC(void, sdallocx, (void *ptr, size_t size, int flags));
// This is guarded by BORINGSSL_SDALLOCX, rather than being a weak symbol,
// because it can work poorly if there are two malloc implementations in the
// address space. (Which probably isn't valid, ODR etc, but
// https://github.com/grpc/grpc/issues/25450). In that situation, |malloc| can
// come from one allocator but |sdallocx| from another and crashes quickly
// result. We can't match |sdallocx| with |mallocx| because tcmalloc only
// provides the former, so a mismatch can still happen.
void sdallocx(void *ptr, size_t size, int flags);
#endif
// The following three functions can be defined to override default heap
// allocation and freeing. If defined, it is the responsibility of
@ -162,11 +166,11 @@ void OPENSSL_free(void *orig_ptr) {
size_t size = *(size_t *)ptr;
OPENSSL_cleanse(ptr, size + OPENSSL_MALLOC_PREFIX);
if (sdallocx) {
sdallocx(ptr, size + OPENSSL_MALLOC_PREFIX, 0 /* flags */);
} else {
free(ptr);
}
#if defined(BORINGSSL_SDALLOCX)
sdallocx(ptr, size + OPENSSL_MALLOC_PREFIX, 0 /* flags */);
#else
free(ptr);
#endif
}
void *OPENSSL_realloc(void *orig_ptr, size_t new_size) {