linux-kernel - [PATCH v7 7/9] crypto: qat: Remove VLA usage

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Message-Id: <20180802225152.19194-8-keescook@chromium.org>
Date:   Thu,  2 Aug 2018 15:51:50 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Kees Cook <keescook@...omium.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        Tudor-Dan Ambarus <tudor.ambarus@...rochip.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Will Deacon <will.deacon@....com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, qat-linux@...el.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH v7 7/9] crypto: qat: Remove VLA usage

In the quest to remove all stack VLA usage from the kernel[1], this uses
the new upper bound for the stack buffer. Also adds a sanity check.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/crypto/qat/qat_common/qat_algs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/qat/qat_common/qat_algs.c b/drivers/crypto/qat/qat_common/qat_algs.c
index 1138e41d6805..a28edf7b792f 100644
--- a/drivers/crypto/qat/qat_common/qat_algs.c
+++ b/drivers/crypto/qat/qat_common/qat_algs.c
@@ -153,8 +153,8 @@ static int qat_alg_do_precomputes(struct icp_qat_hw_auth_algo_blk *hash,
 	struct sha512_state sha512;
 	int block_size = crypto_shash_blocksize(ctx->hash_tfm);
 	int digest_size = crypto_shash_digestsize(ctx->hash_tfm);
-	char ipad[block_size];
-	char opad[block_size];
+	char ipad[MAX_ALGAPI_BLOCKSIZE];
+	char opad[MAX_ALGAPI_BLOCKSIZE];
 	__be32 *hash_state_out;
 	__be64 *hash512_state_out;
 	int i, offset;
@@ -164,6 +164,10 @@ static int qat_alg_do_precomputes(struct icp_qat_hw_auth_algo_blk *hash,
 	shash->tfm = ctx->hash_tfm;
 	shash->flags = 0x0;
 
+	if (WARN_ON(block_size > sizeof(ipad) ||
+		    sizeof(ipad) != sizeof(opad)))
+		return -EINVAL;
+
 	if (auth_keylen > block_size) {
 		int ret = crypto_shash_digest(shash, auth_key,
 					      auth_keylen, ipad);
-- 
2.17.1