Commit 6c2190b3 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker

NFS: Fix listxattr receive buffer size

Certain NFSv4.2/RDMA tests fail with v5.9-rc1.

rpcrdma_convert_kvec() runs off the end of the rl_segments array
because rq_rcv_buf.tail[0].iov_len holds a very large positive
value. The resultant kernel memory corruption is enough to crash
the client system.

Callers of rpc_prepare_reply_pages() must reserve an extra XDR_UNIT
in the maximum decode size for a possible XDR pad of the contents
of the xdr_buf's pages. That guarantees the allocated receive buffer
will be large enough to accommodate the usual contents plus that XDR
pad word.

encode_op_hdr() cannot add that extra word. If it does,
xdr_inline_pages() underruns the length of the tail iovec.

Fixes: 3e1f0212 ("NFSv4.2: add client side XDR handling for extended attributes")
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 70438afb
...@@ -196,7 +196,7 @@ ...@@ -196,7 +196,7 @@
1 + nfs4_xattr_name_maxsz + 1) 1 + nfs4_xattr_name_maxsz + 1)
#define decode_setxattr_maxsz (op_decode_hdr_maxsz + decode_change_info_maxsz) #define decode_setxattr_maxsz (op_decode_hdr_maxsz + decode_change_info_maxsz)
#define encode_listxattrs_maxsz (op_encode_hdr_maxsz + 2 + 1) #define encode_listxattrs_maxsz (op_encode_hdr_maxsz + 2 + 1)
#define decode_listxattrs_maxsz (op_decode_hdr_maxsz + 2 + 1 + 1) #define decode_listxattrs_maxsz (op_decode_hdr_maxsz + 2 + 1 + 1 + 1)
#define encode_removexattr_maxsz (op_encode_hdr_maxsz + 1 + \ #define encode_removexattr_maxsz (op_encode_hdr_maxsz + 1 + \
nfs4_xattr_name_maxsz) nfs4_xattr_name_maxsz)
#define decode_removexattr_maxsz (op_decode_hdr_maxsz + \ #define decode_removexattr_maxsz (op_decode_hdr_maxsz + \
...@@ -531,7 +531,7 @@ static void encode_listxattrs(struct xdr_stream *xdr, ...@@ -531,7 +531,7 @@ static void encode_listxattrs(struct xdr_stream *xdr,
{ {
__be32 *p; __be32 *p;
encode_op_hdr(xdr, OP_LISTXATTRS, decode_listxattrs_maxsz + 1, hdr); encode_op_hdr(xdr, OP_LISTXATTRS, decode_listxattrs_maxsz, hdr);
p = reserve_space(xdr, 12); p = reserve_space(xdr, 12);
if (unlikely(!p)) if (unlikely(!p))
......
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