Re: [PATCH next] crypto: fix oob Read in arc4_crypt

Herbert Xu
2023-12-21T00:19:12Z

On Wed, Dec 20, 2023 at 11:53:55PM +0800, Edward Adam Davis wrote:
> The space allocated to areq is not sufficient to access the member __ctx of
> struct skcipher_request, as the space occupied by struct arc4_ctx for reading
> is 1032 bytes, while the requested memory size in skcipher_recvmsg() is:
> sizeof(struct af_alg_async_req) + crypto_skcipher_reqsize(tfm) = 736 bytes,
> which does not include the memory required for __ctx of struct skcipher_request.

I cannot reproduce this. The total allocated size I get is 1768.

How can crypto_skcipher_reqsize(tfm) return zero?

Thanks,