netdev - Re: [syzbot] [crypto?] general protection fault in shash_async

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Message-ID: <ZIrWOe4pG7M3TJic@gondor.apana.org.au>
Date: Thu, 15 Jun 2023 17:13:29 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: David Howells <dhowells@...hat.com>
Cc: syzbot <syzbot+13a08c0bf4d212766c3c@...kaller.appspotmail.com>,
	davem@...emloft.net, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [crypto?] general protection fault in shash_async_final

On Wed, Jun 14, 2023 at 12:25:14PM +0100, David Howells wrote:
> Here's a reduced testcase for this.  The key seems to be passing MSG_MORE to
> sendmsg() and then not following up with more data before calling recvmsg().
> Apart from not oopsing, I wonder what the behaviour should be here?  Should
> recvmsg() return an error (EAGAIN or ENODATA maybe) or should it close the
> existing operation?

On send if MSG_MORE is set then we don't finalise the hash.

If the user calls recvmsg while the hash hasn't been finalised, then
we will force finalisation (thus rendering the last MSG_MORE moot).

Cheers,
-- 
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