From: Herbert Xu <herbert@gondor.apana.org.au> commit 7db3b61b6bba4310f454588c2ca6faf2958ad79f upstream. We need to check whether spawn->alg is NULL under lock as otherwise the algorithm could be removed from under us after we have checked it and found it to be non-NULL. This could cause us to remove the spawn from a non-existent list. Fixes: 7ede5a5ba55a ("crypto: api - Fix crypto_drop_spawn crash...") Cc: <stable@vger.kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- crypto/algapi.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/crypto/algapi.c b/crypto/algapi.c index a0f9e80..1c96d36 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -676,11 +676,9 @@ int crypto_grab_spawn(struct crypto_spawn *spawn, const char *name, void crypto_drop_spawn(struct crypto_spawn *spawn) { - if (!spawn->alg) - return; - down_write(&crypto_alg_sem); - list_del(&spawn->list); + if (spawn->alg) + list_del(&spawn->list); up_write(&crypto_alg_sem); } EXPORT_SYMBOL_GPL(crypto_drop_spawn); -- 1.8.3