Patch "crypto: algif_aead - fix reference counting of null skcipher" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

crypto: algif_aead - fix reference counting of null skcipher

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
crypto-algif_aead-fix-reference-counting-of-null-skcipher.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Mon, 27 Nov 2017 23:23:05 -0800
Subject: crypto: algif_aead - fix reference counting of null skcipher

From: Eric Biggers <[email protected]>

commit b32a7dc8aef1882fbf983eb354837488cc9d54dc upstream.

In the AEAD interface for AF_ALG, the reference to the "null skcipher" held by each tfm was being dropped in the wrong place -- when each af_alg_ctx was freed instead of when the aead_tfm was freed. As discovered by syzkaller, a specially crafted program could use this to cause the null skcipher to be freed while it is still in use.

Fix it by dropping the reference in the right place.

---
 crypto/algif_aead.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -503,6 +503,7 @@ static void aead_release(void *private)
 	struct aead_tfm *tfm = private;
 
 	crypto_free_aead(tfm->aead);
+	crypto_put_default_null_skcipher2();
 	kfree(tfm);
 }
 

@@ -535,7 +536,6 @@ static void aead_sock_destruct(struct so
 	unsigned int ivlen = crypto_aead_ivsize(tfm);
 
 	af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
-	crypto_put_default_null_skcipher2();
 	sock_kzfree_s(sk, ctx->iv, ivlen);
 	sock_kfree_s(sk, ctx, ctx->len);
 	af_alg_release_parent(sk);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/crypto-algif_aead-fix-reference-counting-of-null-skcipher.patch queue-4.14/crypto-salsa20-fix-blkcipher_walk-api-usage.patch queue-4.14/crypto-rsa-fix-buffer-overread-when-stripping-leading-zeroes.patch queue-4.14/crypto-hmac-require-that-the-underlying-hash-algorithm-is-unkeyed.patch queue-4.14/crypto-af_alg-fix-null-pointer-dereference-in.patch