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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
Subject: [PATCH] crypto: api - Check spawn->alg under lock in crypto_drop_spawn
Date: Fri, 6 Dec 2019 13:55:17 +0800	[thread overview]
Message-ID: <20191206055517.53o7xtpxdo2bx6qe@gondor.apana.org.au> (raw)

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: 6bfd48096ff8 ("[CRYPTO] api: Added spawns")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 783006f4d339..6869feb31c99 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -668,11 +668,9 @@ 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);
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

             reply	other threads:[~2019-12-06  5:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-06  5:55 Herbert Xu [this message]
2019-12-11  3:36 ` [PATCH] crypto: api - Check spawn->alg under lock in crypto_drop_spawn Eric Biggers
2019-12-11  8:27   ` Herbert Xu

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