linux-kernel - [PATCH v4 4/9] crypto: stm32/cryp - fix xts and race condition in crypto

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Message-ID: <20211130075501.21958-5-nicolas.toromanoff@foss.st.com>
Date:   Tue, 30 Nov 2021 08:54:56 +0100
From:   Nicolas Toromanoff <nicolas.toromanoff@...s.st.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>
CC:     Marek Vasut <marex@...x.de>,
        Nicolas Toromanoff <nicolas.toromanoff@...s.st.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        <linux-crypto@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v4 4/9] crypto: stm32/cryp - fix xts and race condition in crypto_engine requests

Don't erase key:
If key is erased before the crypto_finalize_.*_request() call, some
pending process will run with a key={ 0 }.
Moreover if the key is reset at end of request, it breaks xts chaining
mode, as for last xts block (in case input len is not a multiple of
block) a new AES request is started without calling again set_key().

Fixes: 9e054ec21ef8 ("crypto: stm32 - Support for STM32 CRYP crypto module")

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@...s.st.com>
---
 drivers/crypto/stm32/stm32-cryp.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
index ab4a107a0860..b2b553651964 100644
--- a/drivers/crypto/stm32/stm32-cryp.c
+++ b/drivers/crypto/stm32/stm32-cryp.c
@@ -674,8 +674,6 @@ static void stm32_cryp_finish_req(struct stm32_cryp *cryp, int err)
 	else
 		crypto_finalize_skcipher_request(cryp->engine, cryp->req,
 						   err);
-
-	memset(cryp->ctx->key, 0, cryp->ctx->keylen);
 }
 
 static int stm32_cryp_cpu_start(struct stm32_cryp *cryp)
-- 
2.17.1