This is a note to let you know that I've just added the patch titled
crypto: api - Demote BUG_ON() in crypto_unregister_alg() to a WARN_ON()
to the 4.19-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:
crypto-api-demote-bug_on-in-crypto_unregister_alg-to-a-warn_on.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a543ada7db729514ddd3ba4efa45f4c7b802ad85 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@xxxxxxxxxx>
Date: Mon, 13 Mar 2023 10:17:24 +0100
Subject: crypto: api - Demote BUG_ON() in crypto_unregister_alg() to a WARN_ON()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
commit a543ada7db729514ddd3ba4efa45f4c7b802ad85 upstream.
The crypto_unregister_alg() function expects callers to ensure that any
algorithm that is unregistered has a refcnt of exactly 1, and issues a
BUG_ON() if this is not the case. However, there are in fact drivers that
will call crypto_unregister_alg() without ensuring that the refcnt has been
lowered first, most notably on system shutdown. This causes the BUG_ON() to
trigger, which prevents a clean shutdown and hangs the system.
To avoid such hangs on shutdown, demote the BUG_ON() in
crypto_unregister_alg() to a WARN_ON() with early return. Cc stable because
this problem was observed on a 6.2 kernel, cf the link below.
Link: https://lore.kernel.org/r/87r0tyq8ph.fsf@xxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
crypto/algapi.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -419,7 +419,9 @@ int crypto_unregister_alg(struct crypto_
if (ret)
return ret;
- BUG_ON(refcount_read(&alg->cra_refcnt) != 1);
+ if (WARN_ON(refcount_read(&alg->cra_refcnt) != 1))
+ return;
+
if (alg->cra_destroy)
alg->cra_destroy(alg);
Patches currently in stable-queue which might be from toke@xxxxxxxxxx are
queue-4.19/crypto-api-demote-bug_on-in-crypto_unregister_alg-to-a-warn_on.patch
