From de2ed32e01d157f061bfd3f92314729af8ae2c8b Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Thu, 25 Feb 2021 14:49:58 +0000 Subject: [PATCH] malloc: Fix a realloc crash with heap tagging [BZ 27468] _int_free must be called with a chunk that has its tag reset. This was missing in a rare case that could crash when heap tagging is enabled: when in a multi-threaded process the current arena runs out of memory during realloc, but another arena still has space to finish the realloc then _int_free was called without clearing the user allocation tags. Fixes bug 27468. Reviewed-by: DJ Delorie --- malloc/malloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/malloc/malloc.c b/malloc/malloc.c index 1f4bbd8edf..8f8f12c276 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -3446,7 +3446,9 @@ __libc_realloc (void *oldmem, size_t bytes) newp = __libc_malloc (bytes); if (newp != NULL) { - memcpy (newp, oldmem, oldsize - SIZE_SZ); + size_t sz = CHUNK_AVAILABLE_SIZE (oldp) - CHUNK_HDR_SZ; + memcpy (newp, oldmem, sz); + (void) TAG_REGION (chunk2rawmem (oldp), sz); _int_free (ar_ptr, oldp, 0); } } -- 2.43.5