Re: [PATCH] crypto: xts,lrw - fix out-of-bounds write after kmalloc failure

[David Miller]

From: Eric Biggers <ebiggers3@xxxxxxxxx>
Date: Thu, 23 Mar 2017 13:39:46 -0700

> From: Eric Biggers <ebiggers@xxxxxxxxxx>
> 
> In the generic XTS and LRW algorithms, for input data > 128 bytes, a
> temporary buffer is allocated to hold the values to be XOR'ed with the
> data before and after encryption or decryption.  If the allocation
> fails, the fixed-size buffer embedded in the request buffer is meant to
> be used as a fallback --- resulting in more calls to the ECB algorithm,
> but still producing the correct result.  However, we weren't correctly
> limiting subreq->cryptlen in this case, resulting in pre_crypt()
> overrunning the embedded buffer.  Fix this by setting subreq->cryptlen
> correctly.
> 
> Fixes: f1c131b45410 ("crypto: xts - Convert to skcipher")
> Fixes: 700cb3f5fe75 ("crypto: lrw - Convert to skcipher")
> Cc: stable@xxxxxxxxxxxxxxx # v4.10+
> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>

Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>