KASAN: use-after-free Read in macsec_get_iflink (2)

Status: upstream: reported C repro on 2024/11/02 16:17
Reported-by: syzbot+2de3ad92b239326eb338@syzkaller.appspotmail.com
First crash: 692d, last: 21d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: use-after-free Read in macsec_get_iflink (3) origin:lts 19 syz, C error 1 34d 239d 0/2 upstream: reported C repro on 2026/01/29 14:26
android-5-15 KASAN: use-after-free Read in macsec_get_iflink (2) 19 1 524d 524d 0/2 auto-obsoleted due to no activity on 2025/07/19 01:07
android-5-10 KASAN: use-after-free Read in macsec_get_iflink 19 syz error 2 846d 973d 0/2 auto-obsoleted due to no activity on 2024/08/30 07:40
android-5-15 KASAN: use-after-free Read in macsec_get_iflink 19 1 1249d 1249d 0/2 auto-obsoleted due to no activity on 2023/07/24 21:03
upstream KASAN: use-after-free Read in macsec_get_iflink net 19 1 1586d 1582d 22/29 fixed on 2023/02/24 13:50
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/08/05 05:49 15m retest repro android13-5.10-lts report log
2026/08/05 05:49 16m retest repro android13-5.10-lts report log
2026/07/09 08:09 15m retest repro android13-5.10-lts log
2026/05/17 16:45 14m retest repro android13-5.10-lts log
2026/05/17 16:45 15m retest repro android13-5.10-lts log
2026/04/19 05:35 24m retest repro android13-5.10-lts report log
2026/02/24 07:02 17m retest repro android13-5.10-lts report log
2026/02/24 07:02 6m retest repro android13-5.10-lts report log
2026/02/08 04:18 31m retest repro android13-5.10-lts report log
2025/12/16 03:57 7m retest repro android13-5.10-lts report log
▶ ▼ Fix bisection attempts (13)
Created Duration User Patch Repo Result
2026/09/04 12:10 7h14m bisect fix android13-5.10-lts OK (0) job log log
2026/07/19 23:00 1h05m bisect fix android13-5.10-lts OK (0) job log log
2026/06/18 11:40 1h00m bisect fix android13-5.10-lts OK (0) job log log
2026/05/19 05:59 1h17m bisect fix android13-5.10-lts OK (0) job log log
2026/03/26 07:45 59m bisect fix android13-5.10-lts OK (0) job log log
2026/01/18 15:14 1h51m bisect fix android13-5.10-lts OK (0) job log log
2025/11/12 07:09 1h22m bisect fix android13-5.10-lts OK (0) job log log
2025/09/06 16:26 1h43m bisect fix android13-5.10-lts OK (0) job log log
2025/06/29 23:28 1h57m bisect fix android13-5.10-lts OK (0) job log log
2025/05/30 18:32 2h50m bisect fix android13-5.10-lts OK (0) job log log
2025/04/12 03:55 2h54m bisect fix android13-5.10-lts OK (0) job log log
2025/03/07 13:50 3h33m bisect fix android13-5.10-lts OK (0) job log log
2025/01/11 15:59 2h28m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in macsec_get_iflink+0x6d/0x70 drivers/net/macsec.c:3682
Read of size 4 at addr ffff888122f8c100 by task kworker/u4:0/7

CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.10.239-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound linkwatch_event
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 macsec_get_iflink+0x6d/0x70 drivers/net/macsec.c:3682
 dev_get_iflink+0x70/0xc0 net/core/dev.c:824
 default_operstate net/core/link_watch.c:41 [inline]
 rfc2863_policy+0x124/0x2b0 net/core/link_watch.c:53
 linkwatch_do_dev+0x3b/0x140 net/core/link_watch.c:160
 __linkwatch_run_queue+0x4a9/0x7b0 net/core/link_watch.c:213
 linkwatch_event+0x4c/0x60 net/core/link_watch.c:252
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Allocated by task 289:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 ____kasan_kmalloc mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 __kmalloc+0x1a7/0x330 mm/slub.c:4033
 __kmalloc_node include/linux/slab.h:418 [inline]
 kmalloc_node include/linux/slab.h:575 [inline]
 kvmalloc_node+0x88/0x130 mm/util.c:612
 kvmalloc include/linux/mm.h:822 [inline]
 kvzalloc include/linux/mm.h:830 [inline]
 alloc_netdev_mqs+0x88/0xc80 net/core/dev.c:10527
 rtnl_create_link+0x242/0x930 net/core/rtnetlink.c:3195
 veth_newlink+0x278/0xbb0 drivers/net/veth.c:1344
 __rtnl_newlink net/core/rtnetlink.c:3482 [inline]
 rtnl_newlink+0x11bd/0x1640 net/core/rtnetlink.c:3530
 rtnetlink_rcv_msg+0x9db/0xb90 net/core/rtnetlink.c:5610
 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2485
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5628
 netlink_unicast_kernel net/netlink/af_netlink.c:1307 [inline]
 netlink_unicast+0x87c/0xa40 net/netlink/af_netlink.c:1333
 netlink_sendmsg+0x88d/0xb30 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 __sys_sendto+0x41d/0x580 net/socket.c:2006
 __do_sys_sendto net/socket.c:2018 [inline]
 __se_sys_sendto net/socket.c:2014 [inline]
 __x64_sys_sendto+0xe5/0x100 net/socket.c:2014
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 49:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1595 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1621
 slab_free mm/slub.c:3203 [inline]
 kfree+0xc0/0x270 mm/slub.c:4191
 kvfree+0x35/0x40 mm/util.c:647
 netdev_freemem+0x3f/0x60 net/core/dev.c:10481
 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1886
 device_release+0x96/0x1c0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:713 [inline]
 kobject_release lib/kobject.c:744 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x18a/0x270 lib/kobject.c:761
 netdev_run_todo+0xb99/0xd20 net/core/dev.c:10352
 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112
 default_device_exit_batch+0x335/0x390 net/core/dev.c:11288
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x5fb/0xb70 net/core/net_namespace.c:609
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff888122f8c000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 256 bytes inside of
 4096-byte region [ffff888122f8c000, ffff888122f8d000)
The buggy address belongs to the page:
page:ffffea00048be200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x122f88
head:ffffea00048be200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042c00
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 290, ts 31301846332, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5357
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1808 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1869
 new_slab_objects mm/slub.c:2627 [inline]
 ___slab_alloc+0x2a6/0x450 mm/slub.c:2791
 __slab_alloc+0x63/0xa0 mm/slub.c:2831
 slab_alloc_node mm/slub.c:2913 [inline]
 slab_alloc mm/slub.c:2955 [inline]
 __kmalloc_track_caller+0x1ef/0x320 mm/slub.c:4536
 kmemdup+0x26/0x60 mm/util.c:131
 __addrconf_sysctl_register+0xad/0x3d0 net/ipv6/addrconf.c:7031
 addrconf_sysctl_register+0x147/0x1a0 net/ipv6/addrconf.c:7096
 ipv6_add_dev+0xbaf/0x10a0 net/ipv6/addrconf.c:448
 addrconf_notify+0x582/0xe90 net/ipv6/addrconf.c:3567
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410
 call_netdevice_notifiers_info net/core/dev.c:2054 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2066 [inline]
 call_netdevice_notifiers+0x111/0x190 net/core/dev.c:2080
 register_netdevice+0x1043/0x13c0 net/core/dev.c:10087
 veth_newlink+0x853/0xbb0 drivers/net/veth.c:1387
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888122f8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888122f8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888122f8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888122f8c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888122f8c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/18 18:12 android13-5.10-lts 6de38b5f6c2b 88248e14 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
2024/11/02 22:31 android13-5.10-lts e5e5644ea27f f00eed24 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
2024/11/02 16:08 android13-5.10-lts e5e5644ea27f f00eed24 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
2024/11/02 18:08 android13-5.10-lts e5e5644ea27f f00eed24 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
2025/07/18 10:43 android13-5.10-lts 6de38b5f6c2b 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
2024/11/13 09:59 android13-5.10-lts 6a01908517df 62026c85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
2024/11/02 14:33 android13-5.10-lts e5e5644ea27f f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in macsec_get_iflink
* Struck through repros no longer work on HEAD.