| From: Herbert Xu <herbert@gondor.apana.org.au> |
| Date: Fri, 6 Dec 2019 13:55:17 +0800 |
| Subject: crypto: api - Check spawn->alg under lock in crypto_drop_spawn |
| |
| 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...") |
| Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| crypto/algapi.c | 6 ++---- |
| 1 file changed, 2 insertions(+), 4 deletions(-) |
| |
| --- a/crypto/algapi.c |
| +++ b/crypto/algapi.c |
| @@ -618,11 +618,9 @@ EXPORT_SYMBOL_GPL(crypto_init_spawn2); |
| |
| 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); |
