Re: [PATCH] can: bcm: Fix UAF in bcm_proc_show()

[Marc Kleine-Budde]

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
> 
> 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 04/01/2014
> 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
> 
> 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
> 
> 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
> 
> bcm_op is freed before procfs entry be removed in bcm_release(),
> this lead to bcm_proc_show() may read the freed bcm_op.
> 
> Fixes: ffd980f976e7 ("[CAN]: Add broadcast manager (bcm) protocol")
> Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>

Added to linux-can/testing.

Thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
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