5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Amir Goldstein <amir73il@xxxxxxxxx>
[ Upstream commit a37d9a17f099072fe4d3a9048b0321978707a918 ]
Apparently, there are some applications that use IN_DELETE event as an
invalidation mechanism and expect that if they try to open a file with
the name reported with the delete event, that it should not contain the
content of the deleted file.
Commit 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of
d_delete()") moved the fsnotify delete hook before d_delete() so fsnotify
will have access to a positive dentry.
This allowed a race where opening the deleted file via cached dentry
is now possible after receiving the IN_DELETE event.
To fix the regression, create a new hook fsnotify_delete() that takes
the unlinked inode as an argument and use a helper d_delete_notify() to
pin the inode, so we can pass it to fsnotify_delete() after d_delete().
Backporting hint: this regression is from v5.3. Although patch will
apply with only trivial conflicts to v5.4 and v5.10, it won't build,
because fsnotify_delete() implementation is different in each of those
versions (see fsnotify_link()).
A follow up patch will fix the fsnotify_unlink/rmdir() calls in pseudo
filesystem that do not need to call d_delete().
Link: https://lore.kernel.org/r/20220120215305.282577-1-amir73il@xxxxxxxxx
Reported-by: Ivan Delalande <colona@xxxxxxxxxx>
Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/
Fixes: 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()")
Cc: stable@xxxxxxxxxxxxxxx # v5.3+
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
[ cel: adjusted to apply on v5.15.y ]
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/linux/fsnotify.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index c80f448b9b0f2..bb8467cd11ae2 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -240,7 +240,8 @@ static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
- fsnotify_name(dir, mask, inode, &dentry->d_name, 0);
+ fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
+ 0);
}
/**
--
2.43.0
