libceph: fix overflow check in crush_decode()

PATCH New Alex Elder 1 participant 1 message Feb 29, 2012 Ceph common code (libceph)

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Alex Elder

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2012-02-29 04:56 UTC #0 lore raw

PATCH 1/1 libceph: fix overflow check in crush_decode()

The existing overflow check (n > ULONG_MAX / b) didn't work, because n = ULONG_MAX / b would both bypass the check and still overflow the allocation size a + n * b.

The correct check should be (n > (ULONG_MAX - a) / b).

Signed-off-by Xi Wang <[email protected]>

Signed-off-by Sage Weil <[email protected]>

---
 net/ceph/osdmap.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

net/ceph/osdmap.c +2 -1

index fd863fe..29ad46e 100644
@@ -283,7 +283,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
 		ceph_decode_32_safe(p, end, yes, bad);
 #if BITS_PER_LONG == 32
 		err = -EINVAL;
-		if (yes > ULONG_MAX / sizeof(struct crush_rule_step))
+		if (yes > (ULONG_MAX - sizeof(*r))
+			  / sizeof(struct crush_rule_step))
 			goto bad;
 #endif
 		r = c->rules[i] = kmalloc(sizeof(*r) +

Signature · 1 line

1.7.5.4