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Date:   Mon, 17 Jul 2023 09:47:36 +0200
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     YueHaibing <yuehaibing@huawei.com>
Cc:     socketcan@hartkopp.net, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, urs.thuermann@volkswagen.de,
        linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] can: bcm: Fix UAF in bcm_proc_show()
Message-ID: <20230717-uplifted-external-b00b04bbc903-mkl@pengutronix.de>
References: <20230715092543.15548-1-yuehaibing@huawei.com>
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On 15.07.2023 17:25:43, YueHaibing wrote:
> BUG: KASAN: slab-use-after-free in bcm_proc_show+0x969/0xa80
> Read of size 8 at addr ffff888155846230 by task cat/7862
>=20
> CPU: 1 PID: 7862 Comm: cat Not tainted 6.5.0-rc1-00153-gc8746099c197 #230
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/0=
1/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xd5/0x150
>  print_report+0xc1/0x5e0
>  kasan_report+0xba/0xf0
>  bcm_proc_show+0x969/0xa80
>  seq_read_iter+0x4f6/0x1260
>  seq_read+0x165/0x210
>  proc_reg_read+0x227/0x300
>  vfs_read+0x1d5/0x8d0
>  ksys_read+0x11e/0x240
>  do_syscall_64+0x35/0xb0
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>=20
> Allocated by task 7846:
>  kasan_save_stack+0x1e/0x40
>  kasan_set_track+0x21/0x30
>  __kasan_kmalloc+0x9e/0xa0
>  bcm_sendmsg+0x264b/0x44e0
>  sock_sendmsg+0xda/0x180
>  ____sys_sendmsg+0x735/0x920
>  ___sys_sendmsg+0x11d/0x1b0
>  __sys_sendmsg+0xfa/0x1d0
>  do_syscall_64+0x35/0xb0
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>=20
> Freed by task 7846:
>  kasan_save_stack+0x1e/0x40
>  kasan_set_track+0x21/0x30
>  kasan_save_free_info+0x27/0x40
>  ____kasan_slab_free+0x161/0x1c0
>  slab_free_freelist_hook+0x119/0x220
>  __kmem_cache_free+0xb4/0x2e0
>  rcu_core+0x809/0x1bd0
>=20
> bcm_op is freed before procfs entry be removed in bcm_release(),
> this lead to bcm_proc_show() may read the freed bcm_op.
>=20
> Fixes: ffd980f976e7 ("[CAN]: Add broadcast manager (bcm) protocol")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>

Added to linux-can/testing.

Thanks,
Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung N=C3=BCrnberg              | Phone: +49-5121-206917-129 |
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