This is a note to let you know that I've just added the patch titled
fscrypt: destroy keyring after security_sb_delete()
to the 5.15-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:
fscrypt-destroy-keyring-after-security_sb_delete.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ccb820dc7d2236b1af0d54ae038a27b5b6d5ae5a Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@xxxxxxxxxx>
Date: Mon, 13 Mar 2023 15:12:29 -0700
Subject: fscrypt: destroy keyring after security_sb_delete()
From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit ccb820dc7d2236b1af0d54ae038a27b5b6d5ae5a upstream.
fscrypt_destroy_keyring() must be called after all potentially-encrypted
inodes were evicted; otherwise it cannot safely destroy the keyring.
Since inodes that are in-use by the Landlock LSM don't get evicted until
security_sb_delete(), this means that fscrypt_destroy_keyring() must be
called *after* security_sb_delete().
This fixes a WARN_ON followed by a NULL dereference, only possible if
Landlock was being used on encrypted files.
Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: syzbot+93e495f6a4f748827c88@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/00000000000044651705f6ca1e30@xxxxxxxxxx
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230313221231.272498-2-ebiggers@xxxxxxxxxx
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/super.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
--- a/fs/super.c
+++ b/fs/super.c
@@ -450,13 +450,22 @@ void generic_shutdown_super(struct super
cgroup_writeback_umount();
- /* evict all inodes with zero refcount */
+ /* Evict all inodes with zero refcount. */
evict_inodes(sb);
- /* only nonzero refcount inodes can have marks */
+
+ /*
+ * Clean up and evict any inodes that still have references due
+ * to fsnotify or the security policy.
+ */
fsnotify_sb_delete(sb);
- fscrypt_destroy_keyring(sb);
security_sb_delete(sb);
+ /*
+ * Now that all potentially-encrypted inodes have been evicted,
+ * the fscrypt keyring can be destroyed.
+ */
+ fscrypt_destroy_keyring(sb);
+
if (sb->s_dio_done_wq) {
destroy_workqueue(sb->s_dio_done_wq);
sb->s_dio_done_wq = NULL;
Patches currently in stable-queue which might be from ebiggers@xxxxxxxxxx are
queue-5.15/fsverity-remove-wq_unbound-from-fsverity-read-workqueue.patch
queue-5.15/fscrypt-destroy-keyring-after-security_sb_delete.patch
