Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Sun, 22 Jan 2023 16:07:37 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
Cc:     Ard Biesheuvel <ardb@kernel.org>
Subject: [v2 PATCH] crypto: xts - Handle EBUSY correctly
Message-ID: <Y8zuyRTzvwNONaqw@gondor.apana.org.au>
References: <Y8kInrsuWybCTgK0@gondor.apana.org.au>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Y8kInrsuWybCTgK0@gondor.apana.org.au>
Precedence: bulk

v2 fixes a typo in the commit message.

---8<---
As it is xts only handles the special return value of EINPROGRESS,
which means that in all other cases it will free data related to the
request.

However, as the caller of xts may specify MAY_BACKLOG, we also need
to expect EBUSY and treat it in the same way.  Otherwise backlogged
requests will trigger a use-after-free.

Fixes: 8083b1bf8163 ("crypto: xts - add support for ciphertext stealing")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/crypto/xts.c b/crypto/xts.c
index 63c85b9e64e0..de6cbcf69bbd 100644
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -203,12 +203,12 @@ static void xts_encrypt_done(struct crypto_async_request *areq, int err)
 	if (!err) {
 		struct xts_request_ctx *rctx = skcipher_request_ctx(req);
 
-		rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
+		rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 		err = xts_xor_tweak_post(req, true);
 
 		if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
 			err = xts_cts_final(req, crypto_skcipher_encrypt);
-			if (err == -EINPROGRESS)
+			if (err == -EINPROGRESS || err == -EBUSY)
 				return;
 		}
 	}
@@ -223,12 +223,12 @@ static void xts_decrypt_done(struct crypto_async_request *areq, int err)
 	if (!err) {
 		struct xts_request_ctx *rctx = skcipher_request_ctx(req);
 
-		rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
+		rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 		err = xts_xor_tweak_post(req, false);
 
 		if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
 			err = xts_cts_final(req, crypto_skcipher_decrypt);
-			if (err == -EINPROGRESS)
+			if (err == -EINPROGRESS || err == -EBUSY)
 				return;
 		}
 	}
-- 
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