FAILED: patch "[PATCH] ovl: fix recursive oi->lock in ovl_link()" failed to apply to 4.18-stable tree

FAILED: patch "[PATCH] ovl: fix recursive oi->lock in ovl_link()" failed to apply to 4.18-stable tree

[gregkh]

The patch below does not apply to the 4.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 6cd078702f2f33cb6b19a682de3e9184112f1a46 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 18 Oct 2018 09:45:49 +0300
Subject: [PATCH] ovl: fix recursive oi->lock in ovl_link()

linking a non-copied-up file into a non-copied-up parent results in a
nested call to mutex_lock_interruptible(&oi->lock). Fix this by copying up
target parent before ovl_nlink_start(), same as done in ovl_rename().

~/unionmount-testsuite$ ./run --ov -s
~/unionmount-testsuite$ ln /mnt/a/foo100 /mnt/a/dir100/

 WARNING: possible recursive locking detected
 --------------------------------------------
 ln/1545 is trying to acquire lock:
 00000000bcce7c4c (&ovl_i_lock_key[depth]){+.+.}, at:
     ovl_copy_up_start+0x28/0x7d
 but task is already holding lock:
 0000000026d73d5b (&ovl_i_lock_key[depth]){+.+.}, at:
     ovl_nlink_start+0x3c/0xc1

[SzM: this seems to be a false positive, but doing the copy-up first is
harmless and removes the lockdep splat]

Reported-by: syzbot+3ef5c0d1a5cb0b21e6be@syzkaller.appspotmail.com
Fixes: 5f8415d6b87e ("ovl: persistent overlay inode nlink for...")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 276914ae3c60..e1a55ecb7aba 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -663,6 +663,10 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 	if (err)
 		goto out_drop_write;
 
+	err = ovl_copy_up(new->d_parent);
+	if (err)
+		goto out_drop_write;
+
 	if (ovl_is_metacopy_dentry(old)) {
 		err = ovl_set_redirect(old, false);
 		if (err)

Re: FAILED: patch "[PATCH] ovl: fix recursive oi->lock in ovl_link()" failed to apply to 4.18-stable tree

[Amir Goldstein]

[-- Attachment #1: Type: text/plain, Size: 369 bytes --]

On Thu, Nov 15, 2018 at 2:06 AM <gregkh@linuxfoundation.org> wrote:
>
>
> The patch below does not apply to the 4.18-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
>

Attached. Should apply to v4.14 as well.

Thanks,
Amir.

[-- Attachment #2: 0001-stable-ovl-fix-recursive-oi-lock-in-ovl_link.patch --]
[-- Type: text/x-patch, Size: 1872 bytes --]

From 23a290ac1335544c2e74562f21feb5f838e192db Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 18 Oct 2018 09:45:49 +0300
Subject: [PATCH] ovl: fix recursive oi->lock in ovl_link()

commit 6cd078702f2f33cb6b19a682de3e9184112f1a46 upstream.

linking a non-copied-up file into a non-copied-up parent results in a
nested call to mutex_lock_interruptible(&oi->lock). Fix this by copying up
target parent before ovl_nlink_start(), same as done in ovl_rename().

~/unionmount-testsuite$ ./run --ov -s
~/unionmount-testsuite$ ln /mnt/a/foo100 /mnt/a/dir100/

 WARNING: possible recursive locking detected
 --------------------------------------------
 ln/1545 is trying to acquire lock:
 00000000bcce7c4c (&ovl_i_lock_key[depth]){+.+.}, at:
     ovl_copy_up_start+0x28/0x7d
 but task is already holding lock:
 0000000026d73d5b (&ovl_i_lock_key[depth]){+.+.}, at:
     ovl_nlink_start+0x3c/0xc1

[SzM: this seems to be a false positive, but doing the copy-up first is
harmless and removes the lockdep splat]

Reported-by: syzbot+3ef5c0d1a5cb0b21e6be@syzkaller.appspotmail.com
Fixes: 5f8415d6b87e ("ovl: persistent overlay inode nlink for...")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
[amir: backport to v4.18]
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/overlayfs/dir.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index d00e66b2a047..36847411c118 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -661,6 +661,11 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 	if (err)
 		goto out_drop_write;
 
+	err = ovl_copy_up(new->d_parent);
+	if (err)
+		goto out_drop_write;
+
+
 	err = ovl_nlink_start(old, &locked);
 	if (err)
 		goto out_drop_write;
-- 
2.7.4

Re: FAILED: patch "[PATCH] ovl: fix recursive oi->lock in ovl_link()" failed to apply to 4.18-stable tree

[Greg KH]

On Thu, Nov 15, 2018 at 05:08:38AM +0200, Amir Goldstein wrote:
> On Thu, Nov 15, 2018 at 2:06 AM <gregkh@linuxfoundation.org> wrote:
> >
> >
> > The patch below does not apply to the 4.18-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> >
> 
> Attached. Should apply to v4.14 as well.

Now applied, thanks!

greg k-h