[PATCH 1/2] NFSv4: Ensure decode_compound_hdr() sanity checks the tag

trondmy
2021-11-04T21:59:04Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

The server is supposed to return the same tag that the client sends in
the outgoing RPC call, but we should still sanity check the length just
in case.

Reported-by: <rtm@csail.mit.edu>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
fs/nfs/nfs4xdr.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 1e3b1db7afa9..fa01edf19015 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3168,20 +3168,23 @@ static int decode_opaque_inline(struct xdr_stream *xdr, unsigned int *len, char

static int decode_compound_hdr(struct xdr_stream *xdr, struct compound_hdr *hdr)
{
- __be32 *p;
+ ssize_t ret;
+ void *ptr;
+ u32 tmp;

- p = xdr_inline_decode(xdr, 8);
- if (unlikely(!p))
+ if (xdr_stream_decode_u32(xdr, &tmp) < 0)
return -EIO;
- hdr->status = be32_to_cpup(p++);
- hdr->taglen = be32_to_cpup(p);
+ hdr->status = tmp;

- p = xdr_inline_decode(xdr, hdr->taglen + 4);
- if (unlikely(!p))
+ ret = xdr_stream_decode_opaque_inline(xdr, &ptr, NFS4_OPAQUE_LIMIT);
+ if (ret < 0)
+ return -EIO;
+ hdr->taglen = ret;
+ hdr->tag = ptr;
+
+ if (xdr_stream_decode_u32(xdr, &tmp) < 0)
return -EIO;
- hdr->tag = (char *)p;
- p += XDR_QUADLEN(hdr->taglen);
- hdr->nops = be32_to_cpup(p);
+ hdr->nops = tmp;
if (unlikely(hdr->nops < 1))
return nfs4_stat_to_errno(hdr->status);
return 0;
--
2.33.1