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 <xi.wang@xxxxxxxxx>
Signed-off-by: Sage Weil <sage@xxxxxxxxxxxx>
---
net/ceph/osdmap.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index fd863fe..29ad46e 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -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) +
--
1.7.5.4
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