KASAN: use-after-free Read in vlan_dev_get

KASAN: use-after-free Read in vlan_dev_get_iflink
Status: upstream: reported C repro on 2020/04/13 08:02
Reported-by: syzbot+7a5cf69ec079d962792f@syzkaller.appspotmail.com
First crash: 595d, last: 45d

Fix bisection: failed (bisect log)

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	KASAN: use-after-free Read in vlan_dev_get_iflink	C			12	21d	582d	0/1	upstream: reported C repro on 2020/04/25 21:56
upstream	KASAN: use-after-free Read in vlan_dev_get_iflink	C	error	error	13	324d	493d	0/22	upstream: reported C repro on 2020/07/23 18:12

Sample crash report:

netlink: 24 bytes leftover after parsing attributes in process `syz-executor726'.
==================================================================
BUG: KASAN: use-after-free in vlan_dev_get_iflink+0x5f/0x70 net/8021q/vlan_dev.c:771
Read of size 4 at addr ffff88808728e808 by task syz-executor726/6974

CPU: 0 PID: 6974 Comm: syz-executor726 Not tainted 4.19.138-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2fe lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load4_noabort+0x88/0x90 mm/kasan/report.c:432
 vlan_dev_get_iflink+0x5f/0x70 net/8021q/vlan_dev.c:771
 dev_get_iflink+0x73/0xe0 net/core/dev.c:692
 rfc2863_policy+0x1af/0x200 net/core/link_watch.c:43
 linkwatch_do_dev+0x1d/0x110 net/core/link_watch.c:157
 linkwatch_forget_dev+0x16a/0x200 net/core/link_watch.c:223
 netdev_wait_allrefs net/core/dev.c:8878 [inline]
 netdev_run_todo+0x258/0xab0 net/core/dev.c:8974
 rtnl_unlock net/core/rtnetlink.c:117 [inline]
 rtnetlink_rcv_msg+0x460/0xb80 net/core/rtnetlink.c:4779
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg net/socket.c:2160 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446d79
Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 0f 83 db 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007efe67e13d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006dbc78 RCX: 0000000000446d79
RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000003
RBP: 00000000006dbc70 R08: 0000000000000018 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 00000000006dbc7c
R13: 0000000000040000 R14: 0000000000000000 R15: 0705001000000048

Allocated by task 6961:
 __do_kmalloc_node mm/slab.c:3689 [inline]
 __kmalloc_node+0x4c/0x70 mm/slab.c:3696
 kmalloc_node include/linux/slab.h:557 [inline]
 kvmalloc_node+0x61/0xf0 mm/util.c:423
 kvmalloc include/linux/mm.h:577 [inline]
 kvzalloc include/linux/mm.h:585 [inline]
 alloc_netdev_mqs+0x97/0xd50 net/core/dev.c:9138
 rtnl_create_link+0x1d4/0xa40 net/core/rtnetlink.c:2869
 rtnl_newlink+0xf3c/0x15b0 net/core/rtnetlink.c:3131
 rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4778
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg net/socket.c:2160 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6996:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 kvfree+0x59/0x60 mm/util.c:452
 device_release+0x76/0x210 drivers/base/core.c:1061
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x22d/0x350 lib/kobject.c:708
 netdev_run_todo+0x77f/0xab0 net/core/dev.c:8997
 rtnl_unlock net/core/rtnetlink.c:117 [inline]
 rtnetlink_rcv_msg+0x460/0xb80 net/core/rtnetlink.c:4779
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg net/socket.c:2160 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88808728e700
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 264 bytes inside of
 4096-byte region [ffff88808728e700, ffff88808728f700)
The buggy address belongs to the page:
page:ffffea00021ca380 count:1 mapcount:0 mapping:ffff88812c39cdc0 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea00021ca308 ffffea0002231d08 ffff88812c39cdc0
raw: 0000000000000000 ffff88808728e700 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808728e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808728e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808728e800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88808728e880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808728e900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (14):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-linux-4-19	2020/08/08 10:01	linux-4.19.y	961f830af065	ff51e522	.config	log	report	syz	C
ci2-linux-4-19	2020/07/21 01:22	linux-4.19.y	17a87580a885	8caeeeb7	.config	log	report	syz	C
ci2-linux-4-19	2021/08/16 05:00	linux-4.19.y	59456c9cc40c	2489ab88	.config	log	report			info	KASAN: use-after-free Read in vlan_dev_get_iflink
ci2-linux-4-19	2021/07/14 14:22	linux-4.19.y	fcfbdfe9626e	94e0b707	.config	log	report			info	KASAN: use-after-free Read in vlan_dev_get_iflink
ci2-linux-4-19	2021/04/23 10:57	linux-4.19.y	2965db2e004c	590921a5	.config	log	report			info	KASAN: use-after-free Read in vlan_dev_get_iflink
ci2-linux-4-19	2021/03/05 08:53	linux-4.19.y	dfb571610ba3	9d751681	.config	log	report			info	KASAN: use-after-free Read in vlan_dev_get_iflink
ci2-linux-4-19	2021/01/16 07:37	linux-4.19.y	675cc038067f	65a7a854	.config	log	report			info
ci2-linux-4-19	2020/10/31 19:01	linux-4.19.y	f5d8eef067ac	8bc4594f	.config	log	report			info
ci2-linux-4-19	2020/09/25 15:18	linux-4.19.y	d09b80172c22	4a006f63	.config	log	report			info
ci2-linux-4-19	2020/08/25 20:22	linux-4.19.y	d18b78abc0c6	344da168	.config	log	report
ci2-linux-4-19	2020/08/24 15:48	linux-4.19.y	d18b78abc0c6	67b599d1	.config	log	report
ci2-linux-4-19	2020/08/20 01:29	linux-4.19.y	a834132bd465	ed282a3a	.config	log	report
ci2-linux-4-19	2020/07/21 00:06	linux-4.19.y	17a87580a885	8caeeeb7	.config	log	report
ci2-linux-4-19	2020/04/13 08:01	linux-4.19.y	dda0e2920330	17a986e5	.config	log	report