syzbot


KASAN: use-after-free Read in batadv_iv_ogm_queue_add

Status: fixed on 2019/11/23 02:56
Subsystems: batman
[Documentation on labels]
Reported-by: syzbot+0cc629f19ccb8534935b@syzkaller.appspotmail.com
Fix commit: 40e220b4218b batman-adv: Avoid free/alloc race when handling OGM buffer
First crash: 1658d, last: 1624d
Duplicate bugs (1)
duplicates (1):
Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
general protection fault in batadv_iv_ogm_queue_add batman 20 1622d 1635d 0/26 closed as dup on 2019/10/21 06:54
Discussions (8)
Title Replies (including bot) Last reply
[PATCH 4.4 00/93] 4.4.217-rc1 review 100 (100) 2020/03/21 07:12
[PATCH 4.9 00/90] 4.9.217-rc1 review 94 (94) 2020/03/21 00:48
[PATCH 4.14 00/99] 4.14.174-rc1 review 103 (103) 2020/03/21 00:44
[PATCH 3.16 000/136] 3.16.80-rc1 review 140 (140) 2019/12/23 14:00
[PATCH 4.19 000/149] 4.19.82-stable review 169 (169) 2019/11/11 09:36
[PATCH 5.3 000/163] 5.3.9-stable review 174 (174) 2019/11/06 10:49
[PATCH 0/2] pull request for net: batman-adv 2019-10-25 4 (4) 2019/10/28 23:39
KASAN: use-after-free Read in batadv_iv_ogm_queue_add 0 (1) 2019/10/01 03:09
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Read in batadv_iv_ogm_queue_add syz error 63 1485d 1642d 0/1 upstream: reported syz repro on 2019/10/14 17:58

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in memcpy include/linux/string.h:378 [inline]
BUG: KASAN: use-after-free in batadv_iv_ogm_aggregate_new net/batman-adv/bat_iv_ogm.c:544 [inline]
BUG: KASAN: use-after-free in batadv_iv_ogm_queue_add+0x31d/0x1120 net/batman-adv/bat_iv_ogm.c:640
Read of size 52 at addr ffff888062a48180 by task kworker/u4:4/9145

CPU: 1 PID: 9145 Comm: kworker/u4:4 Not tainted 5.4.0-rc5+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 memcpy+0x24/0x50 mm/kasan/common.c:122
 memcpy include/linux/string.h:378 [inline]
 batadv_iv_ogm_aggregate_new net/batman-adv/bat_iv_ogm.c:544 [inline]
 batadv_iv_ogm_queue_add+0x31d/0x1120 net/batman-adv/bat_iv_ogm.c:640
 batadv_iv_ogm_schedule+0xb0b/0xe50 net/batman-adv/bat_iv_ogm.c:813
 batadv_iv_send_outstanding_bat_ogm_packet+0x580/0x760 net/batman-adv/bat_iv_ogm.c:1675
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 9145:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 __do_kmalloc mm/slab.c:3655 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3664
 kmalloc include/linux/slab.h:561 [inline]
 batadv_tvlv_realloc_packet_buff net/batman-adv/tvlv.c:277 [inline]
 batadv_tvlv_container_ogm_append+0x134/0x490 net/batman-adv/tvlv.c:318
 batadv_iv_ogm_schedule+0xc8e/0xe50 net/batman-adv/bat_iv_ogm.c:776
 batadv_iv_send_outstanding_bat_ogm_packet+0x580/0x760 net/batman-adv/bat_iv_ogm.c:1675
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 17582:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3756
 batadv_iv_ogm_iface_disable+0x39/0x80 net/batman-adv/bat_iv_ogm.c:220
 batadv_hardif_disable_interface.cold+0x4b4/0x87b net/batman-adv/hard-interface.c:875
 batadv_softif_destroy_netlink+0xa9/0x130 net/batman-adv/soft-interface.c:1146
 default_device_exit_batch+0x265/0x420 net/core/dev.c:9830
 ops_exit_list.isra.0+0x10c/0x160 net/core/net_namespace.c:175
 cleanup_net+0x52e/0xae0 net/core/net_namespace.c:595
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff888062a48180
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff888062a48180, ffff888062a481c0)
The buggy address belongs to the page:
page:ffffea00018a9200 refcount:1 mapcount:0 mapping:ffff8880aa400380 index:0xffff888062a48b80
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0000400988 ffffea0000405988 ffff8880aa400380
raw: ffff888062a48b80 ffff888062a48000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888062a48080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888062a48100: 00 00 00 00 04 fc fc fc fc fc fc fc fc fc fc fc
>ffff888062a48180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff888062a48200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888062a48280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/11/01 06:07 upstream e472c64aa4fa a41ca8fa .config console log report ci-upstream-kasan-gce
2019/10/18 15:58 upstream 0e2adab6cf28 8c88c9c1 .config console log report ci-upstream-kasan-gce-root
2019/09/29 03:26 net-old faeacb6ddb13 eb6b9855 .config console log report ci-upstream-net-this-kasan-gce
* Struck through repros no longer work on HEAD.