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authorArjun Shankar <arjun@redhat.com>2017-11-30 13:31:45 +0100
committerArjun Shankar <arjun@redhat.com>2017-11-30 13:42:53 +0100
commit34697694e8a93b325b18f25f7dcded55d6baeaf6 (patch)
tree694ad7ce28c06d16baff488f97f09e46d373564a
parent18305fba5575a09063652014cfc483b898d8bdcd (diff)
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Fix integer overflow in malloc when tcache is enabled [BZ #22375]
When the per-thread cache is enabled, __libc_malloc uses request2size (which
does not perform an overflow check) to calculate the chunk size from the
requested allocation size. This leads to an integer overflow causing malloc
to incorrectly return the last successfully allocated block when called with
a very large size argument (close to SIZE_MAX).

This commit uses checked_request2size instead, removing the overflow.
-rw-r--r--ChangeLog6
-rw-r--r--malloc/malloc.c3
2 files changed, 8 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index b55ed22f32..888f9fbd67 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-11-30  Arjun Shankar  <arjun@redhat.com>
+
+	[BZ #22375]
+	* malloc/malloc.c (__libc_malloc): Use checked_request2size
+	instead of request2size.
+
 2017-11-30  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/sparc/sparc32/sparcv9/fpu/multiarch/s_llrint.S
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 79f0e9eac7..0c9e0748b4 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3031,7 +3031,8 @@ __libc_malloc (size_t bytes)
     return (*hook)(bytes, RETURN_ADDRESS (0));
 #if USE_TCACHE
   /* int_free also calls request2size, be careful to not pad twice.  */
-  size_t tbytes = request2size (bytes);
+  size_t tbytes;
+  checked_request2size (bytes, tbytes);
   size_t tc_idx = csize2tidx (tbytes);
 
   MAYBE_INIT_TCACHE ();