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>

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 726e59a9e50f6ad20471895793efdb171aed7dd7..d50b2742f23baeb20d54c44d6919ed126faf74c8 100644 (file)
--- 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) {