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 @@ -493,7 +493,9 @@ void crypto_unregister_alg(struct crypto if (WARN(ret, "Algorithm %s is not registered", alg->cra_driver_name)) return; - 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);
