nfs: check for integer overflow in decode_devicenotify_args()

On 32 bit, if n is too large then "n * sizeof(*args->devs)" could
overflow and args->devs would be smaller than expected.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 726e59a9e50f..d50b2742f23b 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -305,6 +305,10 @@ __be32 decode_devicenotify_args(struct svc_rqst *rqstp,
         n = ntohl(*p++);
         if (n <= 0)
                 goto out;
+        if (n > ULONG_MAX / sizeof(*args->devs)) {
+                status = htonl(NFS4ERR_BADXDR);
+                goto out;
+        }
 
         args->devs = kmalloc(n * sizeof(*args->devs), GFP_KERNEL);
         if (!args->devs) {