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crypto: api - Demote BUG_ON() in crypto_unregister_alg() to a WARN_ON()

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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@toke.dk
Cc: stable@vger.kernel.org
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Toke Høiland-Jørgensen 2023-03-13 10:17:24 +01:00 committed by Herbert Xu
parent e6af5c0c4d
commit a543ada7db
1 changed files with 3 additions and 1 deletions
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4
crypto/algapi.c
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@ -491,7 +491,9 @@ 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);
if (WARN_ON(refcount_read(&alg->cra_refcnt) != 1))
return;
if (alg->cra_destroy)
alg->cra_destroy(alg);