[ 32/44] cifs: fix potential buffer overrun when composing a new options string

From: Greg Kroah-Hartman
Date: Wed Jun 05 2013 - 17:21:12 EST


3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Jeff Layton <jlayton@xxxxxxxxxx>

commit 166faf21bd14bc5c5295a44874bf7f3930c30b20 upstream.

Consider the case where we have a very short ip= string in the original
mount options, and when we chase a referral we end up with a very long
IPv6 address. Be sure to allow for that possibility when estimating the
size of the string to allocate.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Steve French <sfrench@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/cifs/cifs_dfs_ref.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -18,6 +18,7 @@
#include <linux/slab.h>
#include <linux/vfs.h>
#include <linux/fs.h>
+#include <linux/inet.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifsfs.h"
@@ -150,7 +151,8 @@ char *cifs_compose_mount_options(const c
* assuming that we have 'unc=' and 'ip=' in
* the original sb_mountdata
*/
- md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12;
+ md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12 +
+ INET6_ADDRSTRLEN;
mountdata = kzalloc(md_len+1, GFP_KERNEL);
if (mountdata == NULL) {
rc = -ENOMEM;


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