From: Xi Wang <xi.wang@gmail.com>
Date: Thu, 7 Jun 2012 00:35:55 +0000 (-0500)
Subject: libceph: fix overflow in osdmap_decode()
X-Git-Tag: v3.4.20~61
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6b71f61c321b1fe8d35b75ab573ff46c51e59acc;p=platform%2Fkernel%2Flinux-stable.git

libceph: fix overflow in osdmap_decode()

(cherry picked from commit e91a9b639a691e0982088b5954eaafb5a25c8f1c)

On 32-bit systems, a large `n' would overflow `n * sizeof(u32)' and bypass
the check ceph_decode_need(p, end, n * sizeof(u32), bad).  It would also
overflow the subsequent kmalloc() size, leading to out-of-bounds write.

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Alex Elder <elder@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 77abb13..a38ce3f 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -674,6 +674,9 @@ struct ceph_osdmap *osdmap_decode(void **p, void *end)
 		ceph_decode_need(p, end, sizeof(u32) + sizeof(u64), bad);
 		ceph_decode_copy(p, &pgid, sizeof(pgid));
 		n = ceph_decode_32(p);
+		err = -EINVAL;
+		if (n > (UINT_MAX - sizeof(*pg)) / sizeof(u32))
+			goto bad;
 		ceph_decode_need(p, end, n * sizeof(u32), bad);
 		err = -ENOMEM;
 		pg = kmalloc(sizeof(*pg) + n*sizeof(u32), GFP_NOFS);