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authorAmir Goldstein <amir73il@gmail.com>2018-10-18 09:45:49 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-11-21 09:24:06 +0100
commit3c5cf7980bed91cc0f776eb9902b8b6adbe72edc (patch)
tree1acafd4a9cbe18c923727445f998b4bf85cc6b8d
parent78da72ee42d82cfd001e863510eeb270bdd08143 (diff)
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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.c5
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;