linux-kernel - Re: [PATCH net-next v2] crypto: af_alg/hash: Fix recvmsg() after sendmsg(MSG

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Message-ID: <ZJFhX3RYknrkcN0x@gondor.apana.org.au>
Date:   Tue, 20 Jun 2023 16:20:47 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     David Howells <dhowells@...hat.com>
Cc:     netdev@...r.kernel.org,
        syzbot+13a08c0bf4d212766c3c@...kaller.appspotmail.com,
        syzbot+14234ccf6d0ef629ec1a@...kaller.appspotmail.com,
        syzbot+4e2e47f32607d0f72d43@...kaller.appspotmail.com,
        syzbot+472626bb5e7c59fb768f@...kaller.appspotmail.com,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Matthew Wilcox <willy@...radead.org>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2] crypto: af_alg/hash: Fix recvmsg() after
 sendmsg(MSG_MORE)

On Tue, Jun 20, 2023 at 08:42:15AM +0100, David Howells wrote:
>
> Not so.  hash_recvmsg() will call crypto_ahash_init() first because ctx->more
> is false (hence why we came down this branch in hash_sendmsg()) and the result
> was released on the previous line (which you're objecting to).  If it goes to
> the "done" label, it will skip setting ctx->more to true if MSG_MORE is
> passed.

I see, yes it should work.

> However, given you want sendmsg() to do the init->digest cycle on zero length
> data, I think we should revert to the previous version of the patch that makes
> a pass of the loop even with no data.

Let's get this fixed ASAP and we can refine it later.

Acked-by: Herbert Xu <herbert@...dor.apana.org.au>

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt