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| author | Amir Goldstein <amir73il@gmail.com> | 2018-10-18 09:45:49 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-21 09:24:06 +0100 |
| commit | 3c5cf7980bed91cc0f776eb9902b8b6adbe72edc (patch) | |
| tree | 1acafd4a9cbe18c923727445f998b4bf85cc6b8d | |
| parent | 78da72ee42d82cfd001e863510eeb270bdd08143 (diff) | |
| download | linux-stable-3c5cf7980bed91cc0f776eb9902b8b6adbe72edc.tar.gz linux-stable-3c5cf7980bed91cc0f776eb9902b8b6adbe72edc.tar.bz2 linux-stable-3c5cf7980bed91cc0f776eb9902b8b6adbe72edc.zip | |
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/overlayfs/dir.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index cc961a3bd3bd..0568898393f2 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -595,6 +595,11 @@ 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; |