Re: [PATCH] crypto: nx: Fix memcpy() over-reading in nonce
flat view
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2021-06-17 06:08:26
Also in:
linux-crypto, linux-hardening, lkml, stable
Kees Cook [off-list ref] writes:
Fix typo in memcpy() where size should be CTR_RFC3686_NONCE_SIZE.
Fixes: 030f4e968741 ("crypto: nx - Fix reentrancy bugs")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <redacted>Thanks.
quoted hunk ↗ jump to hunk
--- drivers/crypto/nx/nx-aes-ctr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/crypto/nx/nx-aes-ctr.c b/drivers/crypto/nx/nx-aes-ctr.c index 13f518802343..6120e350ff71 100644 --- a/drivers/crypto/nx/nx-aes-ctr.c +++ b/drivers/crypto/nx/nx-aes-ctr.c@@ -118,7 +118,7 @@ static int ctr3686_aes_nx_crypt(struct skcipher_request *req) struct nx_crypto_ctx *nx_ctx = crypto_skcipher_ctx(tfm); u8 iv[16]; - memcpy(iv, nx_ctx->priv.ctr.nonce, CTR_RFC3686_IV_SIZE); + memcpy(iv, nx_ctx->priv.ctr.nonce, CTR_RFC3686_NONCE_SIZE); memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE); iv[12] = iv[13] = iv[14] = 0; iv[15] = 1;
Where IV_SIZE is 8 and NONCE_SIZE is 4. And iv is 16 bytes, so it's not a buffer overflow. But priv.ctr.nonce is 4 bytes, and at the end of the struct, so it reads 4 bytes past the end of the nx_crypto_ctx, which is not good. But then immediately overwrites whatever it read with req->iv. So seems pretty harmless in practice? cheers