KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings (3)

Status: upstream: reported on 2026/08/23 14:50
Reported-by: syzbot+114db26aa907290dea4a@syzkaller.appspotmail.com
First crash: 3d08h, last: 3d08h
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings 19 1 425d 425d 0/2 auto-obsoleted due to no activity on 2025/10/05 22:34
linux-6.6 KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings (2) 19 1 121d 121d 0/2 auto-obsoleted due to no activity on 2026/08/05 06:57
upstream KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings rdma prio:high 19 syz done 44440 now 887d 0/29 upstream: reported syz repro on 2024/03/22 20:10
linux-6.1 KASAN: use-after-free Read in __ethtool_get_link_ksettings 19 7 701d 834d 0/3 auto-obsoleted due to no activity on 2025/01/02 21:40
linux-6.1 KASAN: use-after-free Read in __ethtool_get_link_ksettings (2) 19 5 27d 190d 0/3 upstream: reported on 2026/02/17 03:21
upstream KASAN: use-after-free Read in __ethtool_get_link_ksettings net 19 2 1601d 1638d 0/29 auto-closed as invalid on 2022/07/07 00:01
upstream general protection fault in __ethtool_get_link_ksettings net 7 syz, C error unreliable 298 1869d 2028d 0/29 closed as invalid on 2021/10/06 01:39
upstream KASAN: use-after-free Read in __ethtool_get_link_ksettings (2) net 19 1 1495d 1490d 0/29 auto-obsoleted due to no activity on 2022/11/20 15:32

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x6e/0x180 net/ethtool/ioctl.c:438
Read of size 8 at addr ffff88801e3fc210 by task kworker/0:1/9

CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events smc_ib_port_event_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 __ethtool_get_link_ksettings+0x6e/0x180 net/ethtool/ioctl.c:438
 ib_get_eth_speed+0x17d/0x7e0 drivers/infiniband/core/verbs.c:1984
 rxe_query_port+0x8d/0x2d0 drivers/infiniband/sw/rxe/rxe_verbs.c:62
 __ib_query_port drivers/infiniband/core/device.c:2082 [inline]
 ib_query_port+0x165/0x820 drivers/infiniband/core/device.c:2114
 smc_ib_remember_port_attr net/smc/smc_ib.c:364 [inline]
 smc_ib_port_event_work+0x154/0x920 net/smc/smc_ib.c:388
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Allocated by task 5777:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc_node+0xb6/0x240 mm/slab_common.c:1014
 kmalloc_node include/linux/slab.h:620 [inline]
 kvmalloc_node+0x70/0x180 mm/util.c:617
 kvmalloc include/linux/slab.h:738 [inline]
 kvzalloc include/linux/slab.h:746 [inline]
 alloc_netdev_mqs+0x87/0x1040 net/core/dev.c:10899
 rtnl_create_link+0x310/0xd00 net/core/rtnetlink.c:3393
 rtnl_newlink_create net/core/rtnetlink.c:3519 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3749 [inline]
 rtnl_newlink+0x14ad/0x2170 net/core/rtnetlink.c:3762
 rtnetlink_rcv_msg+0x843/0xf90 net/core/rtnetlink.c:6484
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 59:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
 device_release+0xbc/0x1e0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x21b/0x450 lib/kobject.c:737
 netdev_run_todo+0xcad/0xdb0 net/core/dev.c:10657
 default_device_exit_batch+0x967/0xa00 net/core/dev.c:11779
 ops_exit_list net/core/net_namespace.c:178 [inline]
 cleanup_net+0x792/0xbb0 net/core/net_namespace.c:652
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff88801e3fc000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 528 bytes inside of
 freed 4096-byte region [ffff88801e3fc000, ffff88801e3fd000)

The buggy address belongs to the physical page:
page:ffffea000078fe00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1e3f8
head:ffffea000078fe00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c4f500 dead000000000122 0000000000000000
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 5777, tgid 5777 (syz-executor), ts 86100345385, free_ts 86099171029
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_slab_page+0x5d/0x180 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x11f/0x250 mm/slub.c:3534
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 snmp6_alloc_dev net/ipv6/addrconf.c:354 [inline]
 ipv6_add_dev+0x597/0x11f0 net/ipv6/addrconf.c:404
 addrconf_notify+0x67b/0x1010 net/ipv6/addrconf.c:3652
 notifier_call_chain+0x18f/0x380 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2077 [inline]
 call_netdevice_notifiers net/core/dev.c:2091 [inline]
 register_netdevice+0x1670/0x1ba0 net/core/dev.c:10369
 virt_wifi_newlink+0x395/0x7d0 drivers/net/wireless/virtual/virt_wifi.c:568
 rtnl_newlink_create net/core/rtnetlink.c:3529 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3749 [inline]
 rtnl_newlink+0x15a0/0x2170 net/core/rtnetlink.c:3762
 rtnetlink_rcv_msg+0x843/0xf90 net/core/rtnetlink.c:6484
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x194/0x250 mm/slub.c:3534
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 ref_tracker_alloc+0x163/0x4b0 lib/ref_tracker.c:203
 __netdev_tracker_alloc include/linux/netdevice.h:4149 [inline]
 netdev_hold include/linux/netdevice.h:4178 [inline]
 netdev_queue_add_kobject net/core/net-sysfs.c:1690 [inline]
 netdev_queue_update_kobjects+0x18f/0x480 net/core/net-sysfs.c:1745
 register_queue_kobjects net/core/net-sysfs.c:1806 [inline]
 netdev_register_kobject+0x277/0x320 net/core/net-sysfs.c:2046
 register_netdevice+0x12aa/0x1ba0 net/core/dev.c:10336
 virt_wifi_newlink+0x395/0x7d0 drivers/net/wireless/virtual/virt_wifi.c:568

Memory state around the buggy address:
 ffff88801e3fc100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801e3fc180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801e3fc200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88801e3fc280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801e3fc300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/23 14:50 linux-6.6.y dc6160265ffc 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings
* Struck through repros no longer work on HEAD.