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References: <20240124101404.161655-1-kovalev@altlinux.org> <20240124101404.161655-2-kovalev@altlinux.org>
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From: Eric Dumazet <edumazet@google.com>
Date: Wed, 24 Jan 2024 11:57:47 +0100
Message-ID: <CANn89iLKc8-hwvSBE=aSTRg=52Pn9B0HmFDneGCe6PMawPFCnQ@mail.gmail.com>
Subject: Re: [PATCH 1/1] gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()
To: kovalev@altlinux.org
Cc: pablo@netfilter.org, laforge@gnumonks.org, davem@davemloft.net, 
	kuba@kernel.org, pabeni@redhat.com, osmocom-net-gprs@lists.osmocom.org, 
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org, nickel@altlinux.org, 
	oficerovas@altlinux.org, dutyrok@altlinux.org
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On Wed, Jan 24, 2024 at 11:14=E2=80=AFAM <kovalev@altlinux.org> wrote:
>
> From: Vasiliy Kovalev <kovalev@altlinux.org>
>
> After unloading the module, an instance continues to exist that accesses
> outdated memory addresses.
>
> To prevent this, the dump_pdp_en flag has been added, which blocks the
> dump of pdp contexts by a false value. And only after these checks can
> the net_generic() function be called.
>
> These errors were found using the syzkaller program:
>
> Syzkaller hit 'general protection fault in gtp_genl_dump_pdp' bug.
> gtp: GTP module loaded (pdp ctx size 104 bytes)
> gtp: GTP module unloaded
> general protection fault, probably for non-canonical address
> 0xdffffc0000000001:0000 [#1] SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
> CPU: 0 PID: 2782 Comm: syz-executor139 Not tainted 5.10.200-std-def-alt1 =
#1

Oh wait, this is a 5.10 kernel ?

Please generate a stack trace using a recent tree, it is possible the
bug has been fixed already.