* [PATCH] ceph: fix overflow check in build_snap_context()
@ 2012-02-16 16:56 Xi Wang
0 siblings, 0 replies; only message in thread
From: Xi Wang @ 2012-02-16 16:56 UTC (permalink / raw)
To: Sage Weil; +Cc: ceph-devel, linux-kernel, Xi Wang
The overflow check for a + n * b should be (n > (ULONG_MAX - a) / b),
rather than (n > ULONG_MAX / b - a).
Signed-off-by: Xi Wang <xi.wang@gmail.com>
---
fs/ceph/snap.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index a559c80..f04c096 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -331,7 +331,7 @@ static int build_snap_context(struct ceph_snap_realm *realm)
/* alloc new snap context */
err = -ENOMEM;
- if (num > ULONG_MAX / sizeof(u64) - sizeof(*snapc))
+ if (num > (ULONG_MAX - sizeof(*snapc)) / sizeof(u64))
goto fail;
snapc = kzalloc(sizeof(*snapc) + num*sizeof(u64), GFP_NOFS);
if (!snapc)
--
1.7.5.4
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2012-02-16 16:56 [PATCH] ceph: fix overflow check in build_snap_context() Xi Wang
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