NFSv4: check return value of xdr_inline_decode

Function xdr_inline_decode() will return a NULL pointer if the input
buffer does not have long enough buffer to decode nbytes of data.
However, in function decode_op_map(), the return value of
xdr_inline_decode() is not validated before it is used. This patch adds
a check to the return value of xdr_inline_decode().

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 125212588115..dbfe48ac3529 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -5570,6 +5570,8 @@ static int decode_op_map(struct xdr_stream *xdr, struct nfs4_op_map *op_map)
         unsigned int i;
 
         p = xdr_inline_decode(xdr, 4);
+        if (!p)
+                return -EIO;
         bitmap_words = be32_to_cpup(p++);
         if (bitmap_words > NFS4_OP_MAP_NUM_WORDS)
                 return -EIO;