From 2ad9cf52eb9fea12a19bcf893828e1361a0b6546 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 6 Dec 2012 21:12:28 -0500 Subject: fix invalid read in aligned_alloc in case of mmap-obtained chunks, end points past the end of the mapping and reading it may fault. since the value is not needed until after the conditional, move the access to prevent invalid reads. --- src/malloc/aligned_alloc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'src/malloc') diff --git a/src/malloc/aligned_alloc.c b/src/malloc/aligned_alloc.c index d623420b..158dba41 100644 --- a/src/malloc/aligned_alloc.c +++ b/src/malloc/aligned_alloc.c @@ -31,8 +31,6 @@ void *aligned_alloc(size_t align, size_t len) return NULL; header = ((size_t *)mem)[-1]; - end = mem + (header & -8); - footer = ((size_t *)end)[-2]; new = (void *)((uintptr_t)mem + align-1 & -align); if (!(header & 7)) { @@ -41,6 +39,9 @@ void *aligned_alloc(size_t align, size_t len) return new; } + end = mem + (header & -8); + footer = ((size_t *)end)[-2]; + ((size_t *)mem)[-1] = header&7 | new-mem; ((size_t *)new)[-2] = footer&7 | new-mem; ((size_t *)new)[-1] = header&7 | end-new; -- cgit v1.2.1