syzbot


KASAN: use-after-free Read in hci_send_acl

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+98228e7407314d2d4ba2@syzkaller.appspotmail.com
Fix commit: 5c4c8c954409 Bluetooth: verify AMP hci_chan before amp_destroy
First crash: 859d, last: 648d

Cause bisection: introduced by (bisect log) :
commit 4ffcd582301bd020b1f9d00c55473af305ec19b5
Author: Michael Chan <michael.chan@broadcom.com>
Date: Mon Sep 19 07:58:07 2016 +0000

  bnxt_en: Pad TX packets below 52 bytes.

Crash: KASAN: use-after-free Read in batadv_iv_ogm_queue_add (log)
Repro: C syz .config
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: use-after-free Read in hci_send_acl C done 3 567d 859d 1/1 fixed on 2021/06/23 17:43
linux-4.14 KASAN: use-after-free Read in hci_send_acl C error 4 107d 859d 0/1 upstream: reported C repro on 2020/08/02 14:47

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in hci_send_acl+0xabe/0xc60 net/bluetooth/hci_core.c:3991
Read of size 8 at addr ffff8880a6ff8818 by task kworker/u5:2/6855

CPU: 1 PID: 6855 Comm: kworker/u5:2 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_send_acl+0xabe/0xc60 net/bluetooth/hci_core.c:3991
 l2cap_send_cmd+0x6d5/0x8a0 net/bluetooth/l2cap_core.c:949
 l2cap_send_move_chan_cfm_icid net/bluetooth/l2cap_core.c:4917 [inline]
 l2cap_move_fail net/bluetooth/l2cap_core.c:5401 [inline]
 l2cap_move_channel_rsp net/bluetooth/l2cap_core.c:5440 [inline]
 l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:5719 [inline]
 l2cap_sig_channel net/bluetooth/l2cap_core.c:6418 [inline]
 l2cap_recv_frame+0x6936/0xae10 net/bluetooth/l2cap_core.c:7660
 l2cap_recv_acldata+0x7f6/0x8e0 net/bluetooth/l2cap_core.c:8313
 hci_acldata_packet net/bluetooth/hci_core.c:4520 [inline]
 hci_rx_work+0x4c7/0xb10 net/bluetooth/hci_core.c:4710
 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 6855:
 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
 kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 hci_chan_create+0x9b/0x330 net/bluetooth/hci_conn.c:1692
 l2cap_conn_add.part.0+0x1e/0xe10 net/bluetooth/l2cap_core.c:7699
 l2cap_conn_add net/bluetooth/l2cap_core.c:8139 [inline]
 l2cap_connect_cfm+0x23b/0x1090 net/bluetooth/l2cap_core.c:8097
 hci_connect_cfm include/net/bluetooth/hci_core.h:1340 [inline]
 hci_remote_features_evt net/bluetooth/hci_event.c:3210 [inline]
 hci_event_packet+0x3e01/0x86f5 net/bluetooth/hci_event.c:6061
 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

Freed by task 6855:
 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
 hci_disconn_loglink_complete_evt net/bluetooth/hci_event.c:4999 [inline]
 hci_event_packet+0x319a/0x86f5 net/bluetooth/hci_event.c:6188
 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

The buggy address belongs to the object at ffff8880a6ff8800
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 128-byte region [ffff8880a6ff8800, ffff8880a6ff8880)
The buggy address belongs to the page:
page:ffffea00029bfe00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880a6ff8c00
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002934388 ffff8880aa001540 ffff8880aa000700
raw: ffff8880a6ff8c00 ffff8880a6ff8000 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a6ff8700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a6ff8780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a6ff8800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8880a6ff8880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a6ff8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fix bisection attempts:
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2021/03/01 07:30 upstream fe07bfda2fb9 63a73341 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2021/01/07 16:02 upstream 71c061d24438 63a73341 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/12/07 15:25 upstream 0477e9288185 63a73341 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/11/07 06:59 upstream 659caaf65dc9 63a73341 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/10/08 05:00 upstream c85fb28b6f99 63a73341 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/09/02 16:04 upstream 9c7d619be5a0 63a73341 .config log report syz C
* Struck through repros no longer work on HEAD.
Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2020/08/02 19:29 upstream ac3a0c847296 63a73341 .config log report syz C
ci-upstream-kasan-gce-smack-root 2020/08/02 13:37 upstream ac3a0c847296 63a73341 .config log report syz C
* Struck through repros no longer work on HEAD.