[PATCH 3.2 88/94] ceph: fix overflow check in build_snap_context()
From: Ben Hutchings <hidden>
Date: 2014-08-04 17:14:24
Also in:
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Subsystem:
ceph distributed file system client (ceph), filesystems (vfs and infrastructure), the rest · Maintainers:
Ilya Dryomov, Alex Markuze, Viacheslav Dubeyko, Alexander Viro, Christian Brauner, Linus Torvalds
3.2.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Xi Wang <xi.wang@gmail.com> commit 80834312a4da1405a9bc788313c67643de6fcb4c upstream. 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> Signed-off-by: Sage Weil <redacted> Signed-off-by: Ben Hutchings <redacted> --- fs/ceph/snap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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)