[ 3.5.y.z extended stable ] Patch "nfsd4: fix oops on unusual readlike compound" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    nfsd4: fix oops on unusual readlike compound

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From ec4a48057591c1e907606e6a4ea1509e6036697f Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields at redhat.com>
Date: Tue, 4 Dec 2012 18:25:10 -0500
Subject: [PATCH 16/27] nfsd4: fix oops on unusual readlike compound

commit d5f50b0c290431c65377c4afa1c764e2c3fe5305 upstream.

If the argument and reply together exceed the maximum payload size, then
a reply with a read-like operation can overlow the rq_pages array.

Signed-off-by: J. Bruce Fields <bfields at redhat.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 fs/nfsd/nfs4xdr.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 6322df3..1e83186 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2946,11 +2946,16 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
 	len = maxcount;
 	v = 0;
 	while (len > 0) {
-		pn = resp->rqstp->rq_resused++;
+		pn = resp->rqstp->rq_resused;
+		if (!resp->rqstp->rq_respages[pn]) { /* ran out of pages */
+			maxcount -= len;
+			break;
+		}
 		resp->rqstp->rq_vec[v].iov_base =
 			page_address(resp->rqstp->rq_respages[pn]);
 		resp->rqstp->rq_vec[v].iov_len =
 			len < PAGE_SIZE ? len : PAGE_SIZE;
+		resp->rqstp->rq_resused++;
 		v++;
 		len -= PAGE_SIZE;
 	}
@@ -2996,6 +3001,8 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
 		return nfserr;
 	if (resp->xbuf->page_len)
 		return nfserr_resource;
+	if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
+		return nfserr_resource;

 	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);

@@ -3045,6 +3052,8 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
 		return nfserr;
 	if (resp->xbuf->page_len)
 		return nfserr_resource;
+	if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
+		return nfserr_resource;

 	RESERVE_SPACE(NFS4_VERIFIER_SIZE);
 	savep = p;
--
1.7.9.5