linux-kernel - [PATCH v2 4/8] crypto: stm32/cryp - fix race condition in crypto

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Date:   Tue, 2 Nov 2021 17:47:25 +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 v2 4/8] crypto: stm32/cryp - fix race condition in crypto_engine requests

Erase key after finalizing request.

The key was reseted to 0 before the crypto_finalize_.*_request() call, in
some running path a pending call could run with a key={ 0 }.
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 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
index 9d6ccf1eb4ce..c0903025a4cc 100644
--- a/drivers/crypto/stm32/stm32-cryp.c
+++ b/drivers/crypto/stm32/stm32-cryp.c
@@ -666,6 +666,8 @@ static void stm32_cryp_finish_req(struct stm32_cryp *cryp, int err)
 		free_pages((unsigned long)buf_out, pages);
 	}
 
+	memset(cryp->ctx->key, 0, sizeof(cryp->ctx->key));
+
 	pm_runtime_mark_last_busy(cryp->dev);
 	pm_runtime_put_autosuspend(cryp->dev);
 
@@ -674,8 +676,6 @@ 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