This is a note to let you know that I've just added the patch titled ovl: fix leaked dentry to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ovl-fix-leaked-dentry.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From eaab1d45cdb4bb0c846bd23c3d666d5b90af7b41 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <mic@xxxxxxxxxxxxxxxxxxx> Date: Mon, 29 Mar 2021 18:49:07 +0200 Subject: ovl: fix leaked dentry MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> commit eaab1d45cdb4bb0c846bd23c3d666d5b90af7b41 upstream. Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock: overlayfs: refusing to follow metacopy origin for (/file0) ... BUG: Dentry (____ptrval____){i=3f33,n=file3} still in use (1) [unmount of overlay overlay] ... WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1 ... RIP: 0010:umount_check.cold+0x107/0x14d ... Call Trace: d_walk+0x28c/0x950 ? dentry_lru_isolate+0x2b0/0x2b0 ? __kasan_slab_free+0x12/0x20 do_one_tree+0x33/0x60 shrink_dcache_for_umount+0x78/0x1d0 generic_shutdown_super+0x70/0x440 kill_anon_super+0x3e/0x70 deactivate_locked_super+0xc4/0x160 deactivate_super+0xfa/0x140 cleanup_mnt+0x22e/0x370 __cleanup_mnt+0x1a/0x30 task_work_run+0x139/0x210 do_exit+0xb0c/0x2820 ? __kasan_check_read+0x1d/0x30 ? find_held_lock+0x35/0x160 ? lock_release+0x1b6/0x660 ? mm_update_next_owner+0xa20/0xa20 ? reacquire_held_locks+0x3f0/0x3f0 ? __sanitizer_cov_trace_const_cmp4+0x22/0x30 do_group_exit+0x135/0x380 __do_sys_exit_group.isra.0+0x20/0x20 __x64_sys_exit_group+0x3c/0x50 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae ... VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day... This fix has been tested with a syzkaller reproducer. Cc: Amir Goldstein <amir73il@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v5.8+ Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Fixes: 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()") Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210329164907.2133175-1-mic@xxxxxxxxxxx Reviewed-by: Vivek Goyal <vgoyal@xxxxxxxxxx> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/overlayfs/namei.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -919,6 +919,7 @@ struct dentry *ovl_lookup(struct inode * continue; if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { + dput(this); err = -EPERM; pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry); goto out_put; Patches currently in stable-queue which might be from mic@xxxxxxxxxxxxxxxxxxx are queue-5.11/ovl-fix-leaked-dentry.patch