[Devel] [PATCH RHEL7 COMMIT] ms/ovl: fix recursive oi->lock in ovl_link()
Konstantin Khorenko
khorenko at virtuozzo.com
Mon Dec 3 18:52:32 MSK 2018
The commit is pushed to "branch-rh7-3.10.0-862.20.2.vz7.73.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-862.20.2.vz7.73.17
------>
commit 92f85553310b4c8d70f9388c1c837aabc3f1e9d6
Author: Amir Goldstein <amir73il at gmail.com>
Date: Thu Oct 18 09:45:49 2018 +0300
ms/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 at syzkaller.appspotmail.com
Fixes: 5f8415d6b87e ("ovl: persistent overlay inode nlink for...")
Cc: <stable at vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il at gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi at redhat.com>
https://pmc.acronis.com/browse/VSTOR-18481
(cherry picked from commit 6cd078702f2f33cb6b19a682de3e9184112f1a46)
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
fs/overlayfs/dir.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 7fb210b2c5dc..8147151a6cac 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -638,6 +638,10 @@ 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;
+
err = ovl_nlink_start(old, &locked);
if (err)
goto out_drop_write;
More information about the Devel
mailing list