The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x ccb820dc7d2236b1af0d54ae038a27b5b6d5ae5a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '168000451363159@kroah.com' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

ccb820dc7d22 ("fscrypt: destroy keyring after security_sb_delete()") 83e804f0bfee ("fs,security: Add sb_delete hook")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ccb820dc7d2236b1af0d54ae038a27b5b6d5ae5a Mon Sep 17 00:00:00 2001 From: Eric Biggers ebiggers@google.com Date: Mon, 13 Mar 2023 15:12:29 -0700 Subject: [PATCH] fscrypt: destroy keyring after security_sb_delete()

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@vger.kernel.org Reported-by: syzbot+93e495f6a4f748827c88@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/00000000000044651705f6ca1e30@google.com Reviewed-by: Christian Brauner brauner@kernel.org Link: https://lore.kernel.org/r/20230313221231.272498-2-ebiggers@kernel.org Signed-off-by: Eric Biggers ebiggers@google.com

diff --git a/fs/super.c b/fs/super.c index 84332d5cb817..04bc62ab7dfe 100644 --- a/fs/super.c +++ b/fs/super.c @@ -475,13 +475,22 @@ void generic_shutdown_super(struct super_block *sb)

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;