| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.7 03/69] crypto: arm/aes-ctr - fix NULL dereference in tail processing | Date | Wed, 28 Sep 2016 11:04:45 +0200 |
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4.7-stable review patch. If anyone has any objections, please let me know.
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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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: 86464859cc77 ("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>
--- arch/arm/crypto/aes-ce-glue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm/crypto/aes-ce-glue.c +++ b/arch/arm/crypto/aes-ce-glue.c @@ -284,7 +284,7 @@ static int ctr_encrypt(struct blkcipher_ 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];
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