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[PATCH 0/2] 9p: Fixes for hard-to-hit bugs

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  [PATCH 0/2] 9p: Fixes for hard-to-hit bugs Tuomas Tynkkynen <tuomas@tuxera.com> - 2017-09-06 17:20 +0200
    [PATCH 2/2] net/9p: Switch to wait_event_killable() Tuomas Tynkkynen <tuomas@tuxera.com> - 2017-09-06 17:20 +0200
    [PATCH 1/2] fs/9p: Compare qid.path in v9fs_test_inode Tuomas Tynkkynen <tuomas@tuxera.com> - 2017-09-06 17:20 +0200
    Re: [PATCH 0/2] 9p: Fixes for hard-to-hit bugs Latchesar Ionkov <lucho@ionkov.net> - 2017-09-07 17:00 +0200

#1727591 — [PATCH 0/2] 9p: Fixes for hard-to-hit bugs

These two patches fix two hard-to-hit (but really annoying) bugs in 9p.
The first one was posted earlier in February (with one R-b), the second
is a new one.

Both of these have had soaking in NixOS distribution kernels for
a couple of months with no ill effects.

Tuomas Tynkkynen (2):
  fs/9p: Compare qid.path in v9fs_test_inode
  net/9p: Switch to wait_event_killable()

 fs/9p/vfs_inode.c      |  3 +++
 fs/9p/vfs_inode_dotl.c |  3 +++
 net/9p/client.c        |  3 +--
 net/9p/trans_virtio.c  | 13 ++++++-------
 net/9p/trans_xen.c     |  4 ++--
 5 files changed, 15 insertions(+), 11 deletions(-)

-- 
2.13.0

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#1727592 — [PATCH 2/2] net/9p: Switch to wait_event_killable()

Because userspace gets Very Unhappy when calls like stat() and execve()
return -EINTR on 9p filesystem mounts. For instance, when bash is
looking in PATH for things to execute and some SIGCHLD interrupts
stat(), bash can throw a spurious 'command not found' since it doesn't
retry the stat().

In practice, hitting the problem is rare and needs a really
slow/bogged down 9p server.

Cc: stable@vger.kernel.org
Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
---
 net/9p/client.c       |  3 +--
 net/9p/trans_virtio.c | 13 ++++++-------
 net/9p/trans_xen.c    |  4 ++--
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/net/9p/client.c b/net/9p/client.c
index 4674235b0d9b..1beb131dd3e1 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -773,8 +773,7 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
 	}
 again:
 	/* Wait for the response */
-	err = wait_event_interruptible(*req->wq,
-				       req->status >= REQ_STATUS_RCVD);
+	err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
 
 	/*
 	 * Make sure our req is coherent with regard to updates in other
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index f24b25c25106..f3a4efcf1456 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -286,8 +286,8 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
 		if (err == -ENOSPC) {
 			chan->ring_bufs_avail = 0;
 			spin_unlock_irqrestore(&chan->lock, flags);
-			err = wait_event_interruptible(*chan->vc_wq,
-							chan->ring_bufs_avail);
+			err = wait_event_killable(*chan->vc_wq,
+						  chan->ring_bufs_avail);
 			if (err  == -ERESTARTSYS)
 				return err;
 
@@ -327,7 +327,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan,
 		 * Other zc request to finish here
 		 */
 		if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
-			err = wait_event_interruptible(vp_wq,
+			err = wait_event_killable(vp_wq,
 			      (atomic_read(&vp_pinned) < chan->p9_max_pages));
 			if (err == -ERESTARTSYS)
 				return err;
@@ -471,8 +471,8 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 		if (err == -ENOSPC) {
 			chan->ring_bufs_avail = 0;
 			spin_unlock_irqrestore(&chan->lock, flags);
-			err = wait_event_interruptible(*chan->vc_wq,
-						       chan->ring_bufs_avail);
+			err = wait_event_killable(*chan->vc_wq,
+						  chan->ring_bufs_avail);
 			if (err  == -ERESTARTSYS)
 				goto err_out;
 
@@ -489,8 +489,7 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 	virtqueue_kick(chan->vq);
 	spin_unlock_irqrestore(&chan->lock, flags);
 	p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
-	err = wait_event_interruptible(*req->wq,
-				       req->status >= REQ_STATUS_RCVD);
+	err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
 	/*
 	 * Non kernel buffers are pinned, unpin them
 	 */
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 6ad3e043c617..325c56043007 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -156,8 +156,8 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
 	ring = &priv->rings[num];
 
 again:
-	while (wait_event_interruptible(ring->wq,
-					p9_xen_write_todo(ring, size)) != 0)
+	while (wait_event_killable(ring->wq,
+				   p9_xen_write_todo(ring, size)) != 0)
 		;
 
 	spin_lock_irqsave(&ring->lock, flags);
-- 
2.13.0

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#1727595 — [PATCH 1/2] fs/9p: Compare qid.path in v9fs_test_inode

Commit fd2421f54423 ("fs/9p: When doing inode lookup compare qid details
and inode mode bits.") transformed v9fs_qid_iget() to use iget5_locked()
instead of iget_locked(). However, the test() callback is not checking
fid.path at all, which means that a lookup in the inode cache can now
accidentally locate a completely wrong inode from the same inode hash
bucket if the other fields (qid.type and qid.version) match.

Fixes: fd2421f54423 ("fs/9p: When doing inode lookup compare qid details and inode mode bits.")
Cc: stable@vger.kernel.org
Reviewed-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
---
 fs/9p/vfs_inode.c      | 3 +++
 fs/9p/vfs_inode_dotl.c | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 2a5de610dd8f..bdabb2765d1b 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -483,6 +483,9 @@ static int v9fs_test_inode(struct inode *inode, void *data)
 
 	if (v9inode->qid.type != st->qid.type)
 		return 0;
+
+	if (v9inode->qid.path != st->qid.path)
+		return 0;
 	return 1;
 }
 
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 70f9887c59a9..7f6ae21a27b3 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -87,6 +87,9 @@ static int v9fs_test_inode_dotl(struct inode *inode, void *data)
 
 	if (v9inode->qid.type != st->qid.type)
 		return 0;
+
+	if (v9inode->qid.path != st->qid.path)
+		return 0;
 	return 1;
 }
 
-- 
2.13.0

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#1728249

Acked-by: Latchesar Ionkov <lucho@ionkov.net>

On Wed, Sep 6, 2017 at 8:59 AM, Tuomas Tynkkynen <tuomas@tuxera.com> wrote:
> These two patches fix two hard-to-hit (but really annoying) bugs in 9p.
> The first one was posted earlier in February (with one R-b), the second
> is a new one.
>
> Both of these have had soaking in NixOS distribution kernels for
> a couple of months with no ill effects.
>
> Tuomas Tynkkynen (2):
>   fs/9p: Compare qid.path in v9fs_test_inode
>   net/9p: Switch to wait_event_killable()
>
>  fs/9p/vfs_inode.c      |  3 +++
>  fs/9p/vfs_inode_dotl.c |  3 +++
>  net/9p/client.c        |  3 +--
>  net/9p/trans_virtio.c  | 13 ++++++-------
>  net/9p/trans_xen.c     |  4 ++--
>  5 files changed, 15 insertions(+), 11 deletions(-)
>
> --
> 2.13.0
>

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