Message-ID: <1476436248.31114.21.camel@sipsolutions.net> (sfid-20161014_111138_333756_0E067CDB)
Subject: Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7)
From: Johannes Berg <johannes@sipsolutions.net>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        "linux-next@vger.kernel.org" <linux-next@vger.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Network Development <netdev@vger.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Linux Wireless List <linux-wireless@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jouni Malinen <j@w1.fi>
Date: Fri, 14 Oct 2016 11:10:48 +0200
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On Fri, 2016-10-14 at 10:05 +0100, Ard Biesheuvel wrote:
> 
> Indeed. And the decrypt path does the same for auth_tag[].

Hadn't gotten that far, due to the BUG_ON() in CONFIG_DEBUG_SG in the
encrypt path :)

> But that still means there are two separate problems here, one which
> affects the WPA code, and one that only affects the generic CCM
> chaining mode (but not the accelerated arm64 implementation)

Yes. The generic CCM chaining still doesn't typically have a request on
the stack though. In fact, ESP (net/ipv4/esp4.c) for example will do
temporary allocations with kmalloc for every frame, it seems.

> Unsurprisingly, I would strongly prefer those to be fixed properly
> rather than backing out my patch, but I'm happy to help out whichever
> solution we reach consensus on.

Yeah, obviously, it would be good to use the accelerated versions after
all.

> I will check whether this removes the issue when not using
> crypto/ccm.ko

Ok. I think we can probably live with having those 48 bytes in per-CPU
buffers, but I suppose we don't really want to have ~500.

johannes