On Thu, 2011-03-17 at 19:22 -0400, Trond Myklebust wrote: > On Fri, 2011-03-18 at 10:16 +1100, NeilBrown wrote: > > On Thu, 17 Mar 2011 14:01:05 -0400 Trond Myklebust > > <Trond.Myklebust@xxxxxxxxxx> wrote: > > > > > On Thu, 2011-03-17 at 09:38 +1100, NeilBrown wrote: > > > > We should probably submit a fix to 2.6.37-stable though. For that it > > > > is possibly simplest to tell xdr_decode_inline to round nbytes up to > > > > a multiple of 4 - would you agree? > > > > > > How about the following fix for 2.6.37 stable? > > > > That is good for NFSv3, but NFSv2 has the same problem. Code fragment is > > p = xdr_inline_decode(xdr, entry->len + 4); > > if (unlikely(!p)) > > goto out_overflow; > > entry->name = (const char *) p; > > p += XDR_QUADLEN(entry->len); > > entry->prev_cookie = entry->cookie; > > entry->cookie = ntohl(*p++); > > > > so again we have the cookie after the name and they are decoded together. > > Fair enough. I'll fix that one too. > Here is the result. BTW, those are the only cases we care about in -stable. There are no other callers of xdr_set_scratch_buffer(). 8<--------------------------------------------------------------------------------- >From f71825a9002d4008a5b2ac947bc03b9d7c788557 Mon Sep 17 00:00:00 2001 From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> Date: Thu, 17 Mar 2011 13:42:31 -0400 Subject: [PATCH] NFS: Fix a decoding problem in nfs3_decode_dirent 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@xxxxxxx> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> --- fs/nfs/nfs2xdr.c | 6 ++++-- fs/nfs/nfs3xdr.c | 6 ++++-- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c index b382a1b..33a038d 100644 --- a/fs/nfs/nfs2xdr.c +++ b/fs/nfs/nfs2xdr.c @@ -477,11 +477,13 @@ nfs_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry, struct nfs_se 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++); diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c index ba91236..dcd934f 100644 --- a/fs/nfs/nfs3xdr.c +++ b/fs/nfs/nfs3xdr.c @@ -614,11 +614,13 @@ nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry, struct nfs_s 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); -- 1.7.4 -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
