From 7db3b61b6bba4310f454588c2ca6faf2958ad79f Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 6 Dec 2019 13:55:17 +0800
Subject: [PATCH] crypto: api - Check spawn->alg under lock in crypto_drop_spawn
Git-commit: 7db3b61b6bba4310f454588c2ca6faf2958ad79f
Patch-mainline: v5.6-rc1
References: bsc#1051510
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
crypto/algapi.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/crypto/algapi.c b/crypto/algapi.c
index b052f38edba6..9ecb4a57b342 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -669,11 +669,9 @@ EXPORT_SYMBOL_GPL(crypto_grab_spawn);
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);
--
2.16.4