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DateMon, 21 Mar 2011 16:06:51 -0700
FromGreg KH <>
Subject[52/87] NFS: Fix a decoding problem in nfs3_decode_dirent
2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------
[This needs to be applied to 2.6.37 only. The bug in question was
inadvertently fixed by a series of cleanups in 2.6.38, but the patches
in question are too large to be backported. This patch is a minimal fix
that serves the same purpose.]

When we decode a filename followed by an 8-byte cookie, we need to
consider the fact that the filename and cookie are 32-bit word aligned.
Presently, we may end up copying insufficient amounts of data when
xdr_inline_decode() needs to invoke xdr_copy_to_scratch to deal
with a page boundary.

The following patch fixes the issue by first decoding the filename, and
then decoding the cookie.

Reported-by: Neil Brown <neilb@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/nfs/nfs2xdr.c | 6 ++++--
fs/nfs/nfs3xdr.c | 6 ++++--
2 files changed, 8 insertions(+), 4 deletions(-)
--- a/fs/nfs/nfs2xdr.c
+++ b/fs/nfs/nfs2xdr.c
@@ -477,11 +477,13 @@ nfs_decode_dirent(struct xdr_stream *xdr
entry->ino = ntohl(*p++);
entry->len = ntohl(*p++);

- p = xdr_inline_decode(xdr, entry->len + 4);
+ p = xdr_inline_decode(xdr, entry->len);
if (unlikely(!p))
goto out_overflow;
entry->name = (const char *) p;
- p += XDR_QUADLEN(entry->len);
+ p = xdr_inline_decode(xdr, 4);
+ if (unlikely(!p))
+ goto out_overflow;
entry->prev_cookie = entry->cookie;
entry->cookie = ntohl(*p++);

--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -614,11 +614,13 @@ nfs3_decode_dirent(struct xdr_stream *xd
p = xdr_decode_hyper(p, &entry->ino);
entry->len = ntohl(*p++);

- p = xdr_inline_decode(xdr, entry->len + 8);
+ p = xdr_inline_decode(xdr, entry->len);
if (unlikely(!p))
goto out_overflow;
entry->name = (const char *) p;
- p += XDR_QUADLEN(entry->len);
+ p = xdr_inline_decode(xdr, 8);
+ if (unlikely(!p))
+ goto out_overflow;
entry->prev_cookie = entry->cookie;
p = xdr_decode_hyper(p, &entry->cookie);




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