From 17f487b7afa7cd6c316040f3e6c86dc96b2eec30 Mon Sep 17 00:00:00 2001 From: DJ Delorie Date: Fri, 17 Mar 2017 15:31:38 -0400 Subject: Further harden glibc malloc metadata against 1-byte overflows. Additional check for chunk_size == next->prev->chunk_size in unlink() 2017-03-17 Chris Evans * malloc/malloc.c (unlink): Add consistency check between size and next->prev->size, to further harden against 1-byte overflows. --- malloc/malloc.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'malloc/malloc.c') diff --git a/malloc/malloc.c b/malloc/malloc.c index e29105c372..994a23248e 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1376,6 +1376,8 @@ typedef struct malloc_chunk *mbinptr; /* Take a chunk off a bin list */ #define unlink(AV, P, BK, FD) { \ + if (__builtin_expect (chunksize(P) != prev_size (next_chunk(P)), 0)) \ + malloc_printerr (check_action, "corrupted size vs. prev_size", P, AV); \ FD = P->fd; \ BK = P->bk; \ if (__builtin_expect (FD->bk != P || BK->fd != P, 0)) \ -- cgit v1.2.3