linux-kernel - Re: [RFC PATCH 1/1] net: kcm: Use sk_psock size for kcm_psock

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Message-ID: <20220713111637.7eca089c@kernel.org>
Date:   Wed, 13 Jul 2022 11:16:37 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Khalid Masum <khalid.masum.92@...il.com>
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Pavel Skripkin <paskripkin@...il.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        syzbot+1fa91bcd05206ff8cbb5@...kaller.appspotmail.com
Subject: Re: [RFC PATCH 1/1] net: kcm: Use sk_psock size for kcm_psock_cache

On Wed, 13 Jul 2022 12:32:04 +0600 Khalid Masum wrote:
> `struct sock` has a member `sk_user_data`, which got its memory allocated
> in `kcm_attach` by `kcm_psock_cache` with the size of `kcm_psock`. Which
> is not enough when the member is used as `sk_psock` causing out of bound
> read.
> 
> Use `sk_psock` size to allocate memory instead for `sk_user_data`.
> 
> Reported-by: syzbot+1fa91bcd05206ff8cbb5@...kaller.appspotmail.com
> Signed-off-by: Khalid Masum <khalid.masum.92@...il.com>

Odd CC list, it looks like a netdev problem but netdev@ is not copied.

We had an other parson looking at this on netdev. Is this happening
when legit kernel socket gets mixed with BPF sockmap?

Does this fix work?

https://lore.kernel.org/netdev/165030056960.5073.6664402939918720250.stgit@oracle-102.nfsv4.dev/