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Message-Id: <1523282044-22075-6-git-send-email-s.mesoraca16@gmail.com>
Date: Mon, 9 Apr 2018 15:54:03 +0200
From: Salvatore Mesoraca <s.mesoraca16@...il.com>
To: linux-kernel@...r.kernel.org
Cc: kernel-hardening@...ts.openwall.com,
linux-crypto@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>,
Herbert Xu <herbert@...dor.apana.org.au>,
Kees Cook <keescook@...omium.org>,
Salvatore Mesoraca <s.mesoraca16@...il.com>,
Eric Biggers <ebiggers3@...il.com>,
Laura Abbott <labbott@...hat.com>
Subject: [PATCH 5/6] crypto: cts - avoid VLA use
We avoid 2 VLAs[1] by always allocating MAX_BLOCKSIZE*2 bytes.
We also check the selected cipher at instance creation time, if
it doesn't comply with these limits, the creation will fail.
[1] http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Salvatore Mesoraca <s.mesoraca16@...il.com>
---
crypto/cts.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/crypto/cts.c b/crypto/cts.c
index 4773c18..12e6bd3 100644
--- a/crypto/cts.c
+++ b/crypto/cts.c
@@ -50,6 +50,7 @@
#include <crypto/scatterwalk.h>
#include <linux/slab.h>
#include <linux/compiler.h>
+#include "internal.h"
struct crypto_cts_ctx {
struct crypto_skcipher *child;
@@ -104,7 +105,7 @@ static int cts_cbc_encrypt(struct skcipher_request *req)
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct skcipher_request *subreq = &rctx->subreq;
int bsize = crypto_skcipher_blocksize(tfm);
- u8 d[bsize * 2] __aligned(__alignof__(u32));
+ u8 d[MAX_BLOCKSIZE * 2] __aligned(__alignof__(u32));
struct scatterlist *sg;
unsigned int offset;
int lastn;
@@ -183,7 +184,7 @@ static int cts_cbc_decrypt(struct skcipher_request *req)
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct skcipher_request *subreq = &rctx->subreq;
int bsize = crypto_skcipher_blocksize(tfm);
- u8 d[bsize * 2] __aligned(__alignof__(u32));
+ u8 d[MAX_BLOCKSIZE * 2] __aligned(__alignof__(u32));
struct scatterlist *sg;
unsigned int offset;
u8 *space;
@@ -359,6 +360,9 @@ static int crypto_cts_create(struct crypto_template *tmpl, struct rtattr **tb)
if (crypto_skcipher_alg_ivsize(alg) != alg->base.cra_blocksize)
goto err_drop_spawn;
+ if (alg->base.cra_blocksize > MAX_BLOCKSIZE)
+ goto err_drop_spawn;
+
if (strncmp(alg->base.cra_name, "cbc(", 4))
goto err_drop_spawn;
--
1.9.1
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