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From: Kees Cook <keescook@chromium.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
	Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	Eric Biggers <ebiggers@google.com>,
	Mike Snitzer <snitzer@redhat.com>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	qat-linux@intel.com, linux-kernel@vger.kernel.org,
	dm-devel@redhat.com, linux-crypto@vger.kernel.org,
	Lars Persson <larper@axis.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Alasdair Kergon <agk@redhat.com>, Rabin Vincent <rabinv@axis.com>
Subject: [PATCH v3 1/9] crypto: xcbc: Remove VLA usage
Date: Thu, 28 Jun 2018 17:28:35 -0700	[thread overview]
Message-ID: <20180629002843.31095-2-keescook@chromium.org> (raw)
In-Reply-To: <20180629002843.31095-1-keescook@chromium.org>

In the quest to remove all stack VLA usage from the kernel[1], this uses
the maximum blocksize and adds a sanity check. For xcbc, the blocksize
must always be 16, so use that, since it's already being enforced during
instantiation.

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

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 crypto/xcbc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/crypto/xcbc.c b/crypto/xcbc.c
index 25c75af50d3f..7aa03beed795 100644
--- a/crypto/xcbc.c
+++ b/crypto/xcbc.c
@@ -57,6 +57,8 @@ struct xcbc_desc_ctx {
 	u8 ctx[];
 };
 
+#define XCBC_BLOCKSIZE	16
+
 static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
 				     const u8 *inkey, unsigned int keylen)
 {
@@ -65,7 +67,10 @@ static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
 	int bs = crypto_shash_blocksize(parent);
 	u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 	int err = 0;
-	u8 key1[bs];
+	u8 key1[XCBC_BLOCKSIZE];
+
+	if (WARN_ON(bs > sizeof(key1)))
+		return -EINVAL;
 
 	if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
 		return err;
@@ -212,7 +217,7 @@ static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 		return PTR_ERR(alg);
 
 	switch(alg->cra_blocksize) {
-	case 16:
+	case XCBC_BLOCKSIZE:
 		break;
 	default:
 		goto out_put_alg;
-- 
2.17.1

WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Arnd Bergmann <arnd@arndb.de>, Eric Biggers <ebiggers@google.com>,
	Alasdair Kergon <agk@redhat.com>,
	Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
	Lars Persson <larper@axis.com>, Mike Snitzer <snitzer@redhat.com>,
	Rabin Vincent <rabinv@axis.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	linux-crypto@vger.kernel.org, qat-linux@intel.com,
	dm-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: [PATCH v3 1/9] crypto: xcbc: Remove VLA usage
Date: Thu, 28 Jun 2018 17:28:35 -0700	[thread overview]
Message-ID: <20180629002843.31095-2-keescook@chromium.org> (raw)
In-Reply-To: <20180629002843.31095-1-keescook@chromium.org>

In the quest to remove all stack VLA usage from the kernel[1], this uses
the maximum blocksize and adds a sanity check. For xcbc, the blocksize
must always be 16, so use that, since it's already being enforced during
instantiation.

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

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 crypto/xcbc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/crypto/xcbc.c b/crypto/xcbc.c
index 25c75af50d3f..7aa03beed795 100644
--- a/crypto/xcbc.c
+++ b/crypto/xcbc.c
@@ -57,6 +57,8 @@ struct xcbc_desc_ctx {
 	u8 ctx[];
 };
 
+#define XCBC_BLOCKSIZE	16
+
 static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
 				     const u8 *inkey, unsigned int keylen)
 {
@@ -65,7 +67,10 @@ static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
 	int bs = crypto_shash_blocksize(parent);
 	u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 	int err = 0;
-	u8 key1[bs];
+	u8 key1[XCBC_BLOCKSIZE];
+
+	if (WARN_ON(bs > sizeof(key1)))
+		return -EINVAL;
 
 	if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
 		return err;
@@ -212,7 +217,7 @@ static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 		return PTR_ERR(alg);
 
 	switch(alg->cra_blocksize) {
-	case 16:
+	case XCBC_BLOCKSIZE:
 		break;
 	default:
 		goto out_put_alg;
-- 
2.17.1


  reply	other threads:[~2018-06-29  0:28 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-29  0:28 [PATCH v3 0/9] Crypto: Remove VLA usage (part 1) Kees Cook
2018-06-29  0:28 ` Kees Cook [this message]
2018-06-29  0:28   ` [PATCH v3 1/9] crypto: xcbc: Remove VLA usage Kees Cook
2018-06-29  0:28 ` [PATCH v3 2/9] crypto: cbc: " Kees Cook
2018-06-29  0:28   ` Kees Cook
2018-06-29  0:28 ` [PATCH v3 3/9] crypto: shash: " Kees Cook
2018-06-29  0:28 ` [PATCH v3 4/9] dm integrity: " Kees Cook
2018-06-29 20:43   ` Arnd Bergmann
2018-06-29 20:43     ` Arnd Bergmann
2018-06-29 21:56     ` Kees Cook
2018-06-29 21:56       ` Kees Cook
2018-07-01  6:29       ` Herbert Xu
2018-07-01  6:29         ` Herbert Xu
2018-06-29  0:28 ` [PATCH v3 5/9] crypto: ahash: " Kees Cook
2018-06-29  0:28 ` [PATCH v3 6/9] dm verity fec: " Kees Cook
2018-06-29  0:28 ` [PATCH v3 7/9] crypto alg: Introduce generic max blocksize and alignmask Kees Cook
2018-06-29  0:28 ` [PATCH v3 8/9] crypto: qat: Remove VLA usage Kees Cook
2018-06-29  0:28 ` [PATCH v3 9/9] crypto: shash: Remove VLA usage in unaligned hashing Kees Cook
2018-06-30  7:03   ` [dm-devel] " Eric Biggers
2018-07-01 17:04     ` Kees Cook
2018-07-01 17:20       ` Eric Biggers
2018-07-02 17:34         ` Kees Cook

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