Subject: Re: KASAN: slab-out-of-bounds Read in hci_le_meta_evt

From: Russell King - ARM Linux admin <[email-masked]>
Date: Mon, 3 Aug 2020 18:12:33 +0100

Dear syzbot,

Please explain why you are spamming me with all these reports - four so
far.  I don't understand why you think I should be doing anything with
these.

Thanks.

On Mon, Aug 03, 2020 at 08:05:21AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    5a30a789 Merge tag 'x86-urgent-2020-08-02' of git://git.ke..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11cd21cc900000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c0cfcf935bcc94d2
> dashboard link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10fd4504900000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14aa36a4900000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: [email-masked]
> 
> Bluetooth: hci0: unknown advertising packet type: 0x2b
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in hci_le_direct_adv_report_evt net/bluetooth/hci_event.c:5850 [inline]
> BUG: KASAN: slab-out-of-bounds in hci_le_meta_evt+0x380c/0x3eb0 net/bluetooth/hci_event.c:5914
> Read of size 1 at addr ffff8880a727de0c by task kworker/u5:0/1535
> 
> CPU: 1 PID: 1535 Comm: kworker/u5:0 Not tainted 5.8.0-rc7-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: hci0 hci_rx_work
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x18f/0x20d lib/dump_stack.c:118
>  print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
>  __kasan_report mm/kasan/report.c:513 [inline]
>  kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
>  hci_le_direct_adv_report_evt net/bluetooth/hci_event.c:5850 [inline]
>  hci_le_meta_evt+0x380c/0x3eb0 net/bluetooth/hci_event.c:5914
>  hci_event_packet+0x245a/0x86f5 net/bluetooth/hci_event.c:6167
>  hci_rx_work+0x22e/0xb10 net/bluetooth/hci_core.c:4705
>  process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
>  kthread+0x3b5/0x4a0 kernel/kthread.c:291
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
> 
> Allocated by task 6834:
>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>  set_track mm/kasan/common.c:56 [inline]
>  __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
>  __kmalloc_reserve net/core/skbuff.c:142 [inline]
>  __alloc_skb+0xae/0x550 net/core/skbuff.c:210
>  alloc_skb include/linux/skbuff.h:1083 [inline]
>  bt_skb_alloc include/net/bluetooth/bluetooth.h:377 [inline]
>  vhci_get_user drivers/bluetooth/hci_vhci.c:165 [inline]
>  vhci_write+0xbd/0x450 drivers/bluetooth/hci_vhci.c:285
>  call_write_iter include/linux/fs.h:1908 [inline]
>  new_sync_write+0x422/0x650 fs/read_write.c:503
>  vfs_write+0x59d/0x6b0 fs/read_write.c:578
>  ksys_write+0x12d/0x250 fs/read_write.c:631
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Freed by task 6627:
>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>  set_track mm/kasan/common.c:56 [inline]
>  kasan_set_free_info mm/kasan/common.c:316 [inline]
>  __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
>  __cache_free mm/slab.c:3426 [inline]
>  kfree+0x103/0x2c0 mm/slab.c:3757
>  tomoyo_find_next_domain+0x81d/0x1f77 security/tomoyo/domain.c:885
>  tomoyo_bprm_check_security security/tomoyo/tomoyo.c:101 [inline]
>  tomoyo_bprm_check_security+0x121/0x1a0 security/tomoyo/tomoyo.c:91
>  security_bprm_check+0x45/0xa0 security/security.c:840
>  search_binary_handler fs/exec.c:1737 [inline]
>  exec_binprm fs/exec.c:1790 [inline]
>  __do_execve_file+0x1577/0x2ee0 fs/exec.c:1926
>  do_execveat_common fs/exec.c:1980 [inline]
>  do_execve+0x35/0x50 fs/exec.c:1997
>  __do_sys_execve fs/exec.c:2073 [inline]
>  __se_sys_execve fs/exec.c:2068 [inline]
>  __x64_sys_execve+0x7c/0xa0 fs/exec.c:2068
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> The buggy address belongs to the object at ffff8880a727dc00
>  which belongs to the cache kmalloc-512 of size 512
> The buggy address is located 12 bytes to the right of
>  512-byte region [ffff8880a727dc00, ffff8880a727de00)
> The buggy address belongs to the page:
> page:ffffea00029c9f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
> flags: 0xfffe0000000200(slab)
> raw: 00fffe0000000200 ffffea00029e3848 ffffea0002731b88 ffff8880aa000a80
> raw: 0000000000000000 ffff8880a727d000 0000000100000004 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>  ffff8880a727dd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8880a727dd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff8880a727de00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>                       ^
>  ffff8880a727de80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff8880a727df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at [email-masked].
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!