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authorRich Felker <dalias@aerifal.cx>2012-12-06 21:12:28 -0500
committerRich Felker <dalias@aerifal.cx>2012-12-06 21:12:28 -0500
commit2ad9cf52eb9fea12a19bcf893828e1361a0b6546 (patch)
treece8ba924d60ba567fb8db75b8bd17ab4c89cfeb1 /src/malloc
parent5c5e45e58bd0da2d74aea3e6631b240fedd707ef (diff)
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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.
Diffstat (limited to 'src/malloc')
-rw-r--r--src/malloc/aligned_alloc.c5
1 files changed, 3 insertions, 2 deletions
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;