From: J. Bruce Fields <bfields@redhat.com>
Date: Tue, 4 Dec 2012 23:25:10 +0000 (-0500)
Subject: nfsd4: fix oops on unusual readlike compound
X-Git-Tag: firefly_0821_release~7541^2~197
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d6e0c42ccbb489d73ebc3973583474257a028d66;p=firefly-linux-kernel-4.4.55.git

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@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index f91d58990b65..ecdd18ab3560 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2682,11 +2682,16 @@ 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;
 	}
@@ -2734,6 +2739,8 @@ 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++]);
 
@@ -2783,6 +2790,8 @@ 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(8);  /* verifier */
 	savep = p;