linux-kernel - Re: [PATCH 1/1] gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump

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Message-ID: <CANn89i+mSOtzxOfY=FLhQAj2bZ+a-9KdzivGhBx8_V9YwaAeOw@mail.gmail.com>
Date: Thu, 15 Feb 2024 21:32:42 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: kovalev@...linux.org
Cc: pablo@...filter.org, laforge@...monks.org, davem@...emloft.net, 
	kuba@...nel.org, pabeni@...hat.com, osmocom-net-gprs@...ts.osmocom.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, nickel@...linux.org, 
	oficerovas@...linux.org, dutyrok@...linux.org
Subject: Re: [PATCH 1/1] gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

On Wed, Feb 14, 2024 at 5:50 PM <kovalev@...linux.org> wrote:
>
> 09.02.2024 22:21, Eric Dumazet wrote:
>
> > Maybe, but the patch is not good, I think I and Pablo gave feedback on this ?
> >
> > Please trace __netlink_dump_start() content of control->module
> >
> > gtp_genl_family.module should be set, and we should get it.
> >
> > Otherwise, if the bug is in the core, we would need a dozen of 'work
> > arounds because it is better than nothing'
> >
> > Thank you.
>
> Thanks.
>
> I tracked the moment when the __netlink_dump_start() function was
> called, it turned out that in the gtp_init() initialization function
> before registering pernet subsystem (gtp_net_ops), therefore, outdated
> data is used, which leads to a crash.
>
> The documentation says that ops structure must be assigned before
> registering a generic netlink family [1].
>
> I have fixed and sent a new patch [2].
>
> [1]
> https://elixir.bootlin.com/linux/v6.8-rc4/source/net/netlink/genetlink.c#L773
>
> [2]
> https://lore.kernel.org/netdev/20240214162733.34214-1-kovalev@altlinux.org/T/#u
>

Excellent detective work, thanks a lot !