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Message-Id: <1523282044-22075-5-git-send-email-s.mesoraca16@gmail.com>
Date: Mon, 9 Apr 2018 15:54:02 +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 4/6] crypto: pcbc - avoid VLA use
We avoid 2 VLAs[1] by always allocating MAX_BLOCKSIZE 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/pcbc.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/crypto/pcbc.c b/crypto/pcbc.c
index d9e45a9..797da2f 100644
--- a/crypto/pcbc.c
+++ b/crypto/pcbc.c
@@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/compiler.h>
+#include "internal.h"
struct crypto_pcbc_ctx {
struct crypto_cipher *child;
@@ -72,7 +73,7 @@ static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *iv = walk->iv;
- u8 tmpbuf[bsize];
+ u8 tmpbuf[MAX_BLOCKSIZE];
do {
memcpy(tmpbuf, src, bsize);
@@ -144,7 +145,7 @@ static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *iv = walk->iv;
- u8 tmpbuf[bsize] __aligned(__alignof__(u32));
+ u8 tmpbuf[MAX_BLOCKSIZE] __aligned(__alignof__(u32));
do {
memcpy(tmpbuf, src, bsize);
@@ -251,6 +252,10 @@ static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
if (err)
goto err_drop_spawn;
+ err = -EINVAL;
+ if (alg->cra_blocksize > MAX_BLOCKSIZE)
+ goto err_drop_spawn;
+
inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;
--
1.9.1
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