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() to WARN_ON() in crypto_unregister_alg(). Cc stable because this problem was observed on a 6.2 kernel, cf the link below.

Link: https://lore.kernel.org/r/87r0tyq8ph.fsf@toke.dk Cc: stable@vger.kernel.org Signed-off-by: Toke Høiland-Jørgensen toke@redhat.com --- crypto/algapi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/algapi.c b/crypto/algapi.c index d08f864f08be..e9954fcb61be 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -493,7 +493,7 @@ void crypto_unregister_alg(struct crypto_alg *alg) if (WARN(ret, "Algorithm %s is not registered", alg->cra_driver_name)) return;

- BUG_ON(refcount_read(&alg->cra_refcnt) != 1); + WARN_ON(refcount_read(&alg->cra_refcnt) != 1); if (alg->cra_destroy) alg->cra_destroy(alg);