Patch "nfsd: encoders mustn't use unitialized values in error cases" has been added to the 4.9-stable tree

Patch "nfsd: encoders mustn't use unitialized values in error cases" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    nfsd: encoders mustn't use unitialized values in error cases

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-encoders-mustn-t-use-unitialized-values-in-error-cases.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From f961e3f2acae94b727380c0b74e2d3954d0edf79 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Fri, 5 May 2017 16:17:57 -0400
Subject: nfsd: encoders mustn't use unitialized values in error cases

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

commit f961e3f2acae94b727380c0b74e2d3954d0edf79 upstream.

In error cases, lgp->lg_layout_type may be out of bounds; so we
shouldn't be using it until after the check of nfserr.

This was seen to crash nfsd threads when the server receives a LAYOUTGET
request with a large layout type.

GETDEVICEINFO has the same problem.

Reported-by: Ari Kauppi <Ari.Kauppi@synopsys.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfsd/nfs4xdr.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4081,8 +4081,7 @@ nfsd4_encode_getdeviceinfo(struct nfsd4_
 		struct nfsd4_getdeviceinfo *gdev)
 {
 	struct xdr_stream *xdr = &resp->xdr;
-	const struct nfsd4_layout_ops *ops =
-		nfsd4_layout_ops[gdev->gd_layout_type];
+	const struct nfsd4_layout_ops *ops;
 	u32 starting_len = xdr->buf->len, needed_len;
 	__be32 *p;
 
@@ -4099,6 +4098,7 @@ nfsd4_encode_getdeviceinfo(struct nfsd4_
 
 	/* If maxcount is 0 then just update notifications */
 	if (gdev->gd_maxcount != 0) {
+		ops = nfsd4_layout_ops[gdev->gd_layout_type];
 		nfserr = ops->encode_getdeviceinfo(xdr, gdev);
 		if (nfserr) {
 			/*
@@ -4151,8 +4151,7 @@ nfsd4_encode_layoutget(struct nfsd4_comp
 		struct nfsd4_layoutget *lgp)
 {
 	struct xdr_stream *xdr = &resp->xdr;
-	const struct nfsd4_layout_ops *ops =
-		nfsd4_layout_ops[lgp->lg_layout_type];
+	const struct nfsd4_layout_ops *ops;
 	__be32 *p;
 
 	dprintk("%s: err %d\n", __func__, nfserr);
@@ -4175,6 +4174,7 @@ nfsd4_encode_layoutget(struct nfsd4_comp
 	*p++ = cpu_to_be32(lgp->lg_seg.iomode);
 	*p++ = cpu_to_be32(lgp->lg_layout_type);
 
+	ops = nfsd4_layout_ops[lgp->lg_layout_type];
 	nfserr = ops->encode_layoutget(xdr, lgp);
 out:
 	kfree(lgp->lg_content);


Patches currently in stable-queue which might be from bfields@redhat.com are

queue-4.9/nfsd-check-for-oversized-nfsv2-v3-arguments.patch
queue-4.9/nfsd-encoders-mustn-t-use-unitialized-values-in-error-cases.patch
queue-4.9/nfsd-fix-undefined-behavior-in-nfsd4_layout_verify.patch
queue-4.9/nfsd-fix-up-the-supattr_exclcreat-attributes.patch