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authorAmir Goldstein <amir73il@gmail.com>2024-04-05 17:56:35 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2024-04-14 06:55:46 -0400
commit16b52bbee4823b01ab7fe3919373c981a38f3797 (patch)
treece7a54dd66475297874f9a14c370bb8a6aabb9c6 /fs
parentfec50db7033ea478773b159e0e2efb135270e3b7 (diff)
kernfs: annotate different lockdep class for of->mutex of writable files
The writable file /sys/power/resume may call vfs lookup helpers for arbitrary paths and readonly files can be read by overlayfs from vfs helpers when sysfs is a lower layer of overalyfs. To avoid a lockdep warning of circular dependency between overlayfs inode lock and kernfs of->mutex, use a different lockdep class for writable and readonly kernfs files. Reported-by: syzbot+9a5b0ced8b1bfb238b56@syzkaller.appspotmail.com Fixes: 0fedefd4c4e3 ("kernfs: sysfs: support custom llseek method for sysfs entries") Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/kernfs/file.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e9df2f87072c..8502ef68459b 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -636,11 +636,18 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
* each file a separate locking class. Let's differentiate on
* whether the file has mmap or not for now.
*
- * Both paths of the branch look the same. They're supposed to
+ * For similar reasons, writable and readonly files are given different
+ * lockdep key, because the writable file /sys/power/resume may call vfs
+ * lookup helpers for arbitrary paths and readonly files can be read by
+ * overlayfs from vfs helpers when sysfs is a lower layer of overalyfs.
+ *
+ * All three cases look the same. They're supposed to
* look that way and give @of->mutex different static lockdep keys.
*/
if (has_mmap)
mutex_init(&of->mutex);
+ else if (file->f_mode & FMODE_WRITE)
+ mutex_init(&of->mutex);
else
mutex_init(&of->mutex);