[ 41/80] nfsd4: fix oops on unusual readlike compound

Greg Kroah-Hartman
2013-01-09T20:39:27Z

From: "J. Bruce Fields" <bfields@redhat.com>

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>

---
fs/nfsd/nfs4xdr.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2920,11 +2920,16 @@ nfsd4_encode_read(struct nfsd4_compoundr
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;
}
@@ -2970,6 +2975,8 @@ nfsd4_encode_readlink(struct nfsd4_compo
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++]);

@@ -3019,6 +3026,8 @@ nfsd4_encode_readdir(struct nfsd4_compou
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;