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Date: Wed, 21 Feb 2024 17:07:44 +0800
From: Herbert Xu <herbert@gondor.apana.org.au>
To: syzbot <syzbot+b90b904ef6bdfdafec1d@syzkaller.appspotmail.com>
Cc: davem@davemloft.net, linux-crypto@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [PATCH] crypto: lskcipher - Copy IV in lskcipher glue code always
Message-ID: <ZdW9YBgTtaXo7DGQ@gondor.apana.org.au>
References: <00000000000097f7f90611d1370c@google.com>
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In-Reply-To: <00000000000097f7f90611d1370c@google.com>

The lskcipher glue code for skcipher needs to copy the IV every
time rather than only on the first and last request.  Otherwise
those algorithms that use IV to perform chaining may break, e.g.,
CBC.

This is because crypto_skcipher_import/export do not include the
IV as part of the saved state.

Reported-by: syzbot+b90b904ef6bdfdafec1d@syzkaller.appspotmail.com
Fixes: 662ea18d089b ("crypto: skcipher - Make use of internal state")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/lskcipher.c b/crypto/lskcipher.c
index 0b6dd8aa21f2..0f1bd7dcde24 100644
--- a/crypto/lskcipher.c
+++ b/crypto/lskcipher.c
@@ -212,13 +212,12 @@ static int crypto_lskcipher_crypt_sg(struct skcipher_request *req,
 
 	ivsize = crypto_lskcipher_ivsize(tfm);
 	ivs = PTR_ALIGN(ivs, crypto_skcipher_alignmask(skcipher) + 1);
+	memcpy(ivs, req->iv, ivsize);
 
 	flags = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 
 	if (req->base.flags & CRYPTO_SKCIPHER_REQ_CONT)
 		flags |= CRYPTO_LSKCIPHER_FLAG_CONT;
-	else
-		memcpy(ivs, req->iv, ivsize);
 
 	if (!(req->base.flags & CRYPTO_SKCIPHER_REQ_NOTFINAL))
 		flags |= CRYPTO_LSKCIPHER_FLAG_FINAL;
@@ -234,8 +233,7 @@ static int crypto_lskcipher_crypt_sg(struct skcipher_request *req,
 		flags |= CRYPTO_LSKCIPHER_FLAG_CONT;
 	}
 
-	if (flags & CRYPTO_LSKCIPHER_FLAG_FINAL)
-		memcpy(req->iv, ivs, ivsize);
+	memcpy(req->iv, ivs, ivsize);
 
 	return err;
 }
-- 
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