Re: [PATCH net] Bluetooth: validate setsockopt(RFCOMM_LM) user input

[Simon Horman <horms@kernel.org>]

On Thu, Apr 04, 2024 at 12:47:23PM +0000, Eric Dumazet wrote:
> syzbot reported rfcomm_sock_setsockopt_old() is copying data without
> checking user input length.
> 
>  BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
>  BUG: KASAN: slab-out-of-bounds in copy_from_sockptr include/linux/sockptr.h:55 [inline]
>  BUG: KASAN: slab-out-of-bounds in rfcomm_sock_setsockopt_old net/bluetooth/rfcomm/sock.c:632 [inline]
>  BUG: KASAN: slab-out-of-bounds in rfcomm_sock_setsockopt+0x893/0xa70 net/bluetooth/rfcomm/sock.c:673
> Read of size 4 at addr ffff8880209a8bc3 by task syz-executor632/5064
> 
> CPU: 0 PID: 5064 Comm: syz-executor632 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
>  <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>   print_address_description mm/kasan/report.c:377 [inline]
>   print_report+0x169/0x550 mm/kasan/report.c:488
>   kasan_report+0x143/0x180 mm/kasan/report.c:601
>   copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
>   copy_from_sockptr include/linux/sockptr.h:55 [inline]
>   rfcomm_sock_setsockopt_old net/bluetooth/rfcomm/sock.c:632 [inline]
>   rfcomm_sock_setsockopt+0x893/0xa70 net/bluetooth/rfcomm/sock.c:673
>   do_sock_setsockopt+0x3af/0x720 net/socket.c:2311
>   __sys_setsockopt+0x1ae/0x250 net/socket.c:2334
>   __do_sys_setsockopt net/socket.c:2343 [inline]
>   __se_sys_setsockopt net/socket.c:2340 [inline]
>   __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
>  do_syscall_64+0xfb/0x240
>  entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f36ff898dc9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffe010c2208 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f36ff898dc9
> RDX: 0000000000000003 RSI: 0000000000000012 RDI: 0000000000000006
> RBP: 0000000000000006 R08: 0000000000000002 R09: 0000000000000000
> R10: 00000000200000c0 R11: 0000000000000246 R12: 0000555567399338
> R13: 000000000000000e R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
> 
> Allocated by task 5064:
>   kasan_save_stack mm/kasan/common.c:47 [inline]
>   kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
>   poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
>   __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
>   kasan_kmalloc include/linux/kasan.h:211 [inline]
>   __do_kmalloc_node mm/slub.c:3966 [inline]
>   __kmalloc+0x233/0x4a0 mm/slub.c:3979
>   kmalloc include/linux/slab.h:632 [inline]
>   __cgroup_bpf_run_filter_setsockopt+0xd2f/0x1040 kernel/bpf/cgroup.c:1869
>   do_sock_setsockopt+0x6b4/0x720 net/socket.c:2293
>   __sys_setsockopt+0x1ae/0x250 net/socket.c:2334
>   __do_sys_setsockopt net/socket.c:2343 [inline]
>   __se_sys_setsockopt net/socket.c:2340 [inline]
>   __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
>  do_syscall_64+0xfb/0x240
>  entry_SYSCALL_64_after_hwframe+0x6d/0x75
> 
> The buggy address belongs to the object at ffff8880209a8bc0
>  which belongs to the cache kmalloc-8 of size 8
> The buggy address is located 1 bytes to the right of
>  allocated 2-byte region [ffff8880209a8bc0, ffff8880209a8bc2)
> 
> The buggy address belongs to the physical page:
> page:ffffea0000826a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x209a8
> flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
> page_type: 0xffffffff()
> raw: 00fff00000000800 ffff888014c41280 ffffea000081fb80 dead000000000002
> raw: 0000000000000000 0000000080800080 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, tgid 1 (swapper/0), ts 9917548498, free_ts 0
>   set_page_owner include/linux/page_owner.h:31 [inline]
>   post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533
>   prep_new_page mm/page_alloc.c:1540 [inline]
>   get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311
>   __alloc_pages+0x256/0x680 mm/page_alloc.c:4569
>   __alloc_pages_node include/linux/gfp.h:238 [inline]
>   alloc_pages_node include/linux/gfp.h:261 [inline]
>   alloc_slab_page+0x5f/0x160 mm/slub.c:2175
>   allocate_slab mm/slub.c:2338 [inline]
>   new_slab+0x84/0x2f0 mm/slub.c:2391
>   ___slab_alloc+0xc73/0x1260 mm/slub.c:3525
>   __slab_alloc mm/slub.c:3610 [inline]
>   __slab_alloc_node mm/slub.c:3663 [inline]
>   slab_alloc_node mm/slub.c:3835 [inline]
>   __do_kmalloc_node mm/slub.c:3965 [inline]
>   __kmalloc+0x2e5/0x4a0 mm/slub.c:3979
>   kmalloc_array include/linux/slab.h:665 [inline]
>   kcalloc include/linux/slab.h:696 [inline]
>   group_cpus_evenly+0x294/0x5f0 lib/group_cpus.c:365
>   blk_mq_map_queues+0x4c/0x3e0 block/blk-mq-cpumap.c:23
>   blk_mq_alloc_tag_set+0x7ac/0xf40 block/blk-mq.c:4521
>   nbd_dev_add+0x367/0xc80 drivers/block/nbd.c:1831
>   nbd_init+0x224/0x2e0 drivers/block/nbd.c:2593
>   do_one_initcall+0x238/0x830 init/main.c:1241
>   do_initcall_level+0x157/0x210 init/main.c:1303
>   do_initcalls+0x3f/0x80 init/main.c:1319
>   kernel_init_freeable+0x435/0x5d0 init/main.c:1550
> page_owner free stack trace missing
> 
> Memory state around the buggy address:
>  ffff8880209a8a80: 06 fc fc fc 06 fc fc fc 06 fc fc fc 07 fc fc fc
>  ffff8880209a8b00: fa fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
> >ffff8880209a8b80: fa fc fc fc fa fc fc fc 02 fc fc fc fa fc fc fc
>                                            ^
>  ffff8880209a8c00: 00 fc fc fc 00 fc fc fc 00 fc fc fc 05 fc fc fc
>  ffff8880209a8c80: 05 fc fc fc 05 fc fc fc fa fc fc fc 00 fc fc fc
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Marcel Holtmann <marcel@holtmann.org>
> Cc: Johan Hedberg <johan.hedberg@gmail.com>
> Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com> (supporter:BLUETOOTH SUBSYSTEM)
> Cc: linux-bluetooth@vger.kernel.org

Reviewed-by: Simon Horman <horms@kernel.org>