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crypto: arm/aes-ctr - fix NULL dereference in tail processing

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commit f82e90b28654804ab72881d577d87c3d5c65e2bc upstream.

The AES-CTR glue code avoids calling into the blkcipher API for the
tail portion of the walk, by comparing the remainder of walk.nbytes
modulo AES_BLOCK_SIZE with the residual nbytes, and jumping straight
into the tail processing block if they are equal. This tail processing
block checks whether nbytes != 0, and does nothing otherwise.

However, in case of an allocation failure in the blkcipher layer, we
may enter this code with walk.nbytes == 0, while nbytes > 0. In this
case, we should not dereference the source and destination pointers,
since they may be NULL. So instead of checking for nbytes != 0, check
for (walk.nbytes % AES_BLOCK_SIZE) != 0, which implies the former in
non-error conditions.

Fixes: 86464859cc ("crypto: arm - AES in ECB/CBC/CTR/XTS modes using ARMv8 Crypto Extensions")
Reported-by: xiakaixu <xiakaixu@huawei.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ard Biesheuvel 2016-09-13 09:48:52 +01:00 • committed by Greg Kroah-Hartman
parent 3e2d986d8b
commit 9246fd26f9
1 changed files with 1 additions and 1 deletions
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2
arch/arm/crypto/aes-ce-glue.c
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@ -279,7 +279,7 @@ static int ctr_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
err = blkcipher_walk_done(desc, &walk,
walk.nbytes % AES_BLOCK_SIZE);
}
if (nbytes) {
if (walk.nbytes % AES_BLOCK_SIZE) {
u8 *tdst = walk.dst.virt.addr + blocks * AES_BLOCK_SIZE;
u8 *tsrc = walk.src.virt.addr + blocks * AES_BLOCK_SIZE;
u8 __aligned(8) tail[AES_BLOCK_SIZE];