From 7f9290f72168ad4179bfbf03b9e26d9c75bfc446 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 9 Apr 2019 23:46:31 -0700 Subject: [PATCH] crypto: arm/aes-neonbs - don't access already-freed walk.iv commit 767f015ea0b7ab9d60432ff6cd06b664fd71f50f upstream. If the user-provided IV needs to be aligned to the algorithm's alignmask, then skcipher_walk_virt() copies the IV into a new aligned buffer walk.iv. But skcipher_walk_virt() can fail afterwards, and then if the caller unconditionally accesses walk.iv, it's a use-after-free. arm32 xts-aes-neonbs doesn't set an alignmask, so currently it isn't affected by this despite unconditionally accessing walk.iv. However this is more subtle than desired, and it was actually broken prior to the alignmask being removed by commit cc477bf64573 ("crypto: arm/aes - replace bit-sliced OpenSSL NEON code"). Thus, update xts-aes-neonbs to start checking the return value of skcipher_walk_virt(). Fixes: e4e7f10bfc40 ("ARM: add support for bit sliced AES using NEON instructions") Cc: # v3.13+ Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- arch/arm/crypto/aesbs-glue.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/crypto/aesbs-glue.c b/arch/arm/crypto/aesbs-glue.c index 5d934a0039d7..cb2486a526e6 100644 --- a/arch/arm/crypto/aesbs-glue.c +++ b/arch/arm/crypto/aesbs-glue.c @@ -265,6 +265,8 @@ static int aesbs_xts_encrypt(struct blkcipher_desc *desc, blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt_block(desc, &walk, 8 * AES_BLOCK_SIZE); + if (err) + return err; /* generate the initial tweak */ AES_encrypt(walk.iv, walk.iv, &ctx->twkey); @@ -289,6 +291,8 @@ static int aesbs_xts_decrypt(struct blkcipher_desc *desc, blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt_block(desc, &walk, 8 * AES_BLOCK_SIZE); + if (err) + return err; /* generate the initial tweak */ AES_encrypt(walk.iv, walk.iv, &ctx->twkey); -- 2.20.1