KASAN: use-after-free Read in br_switchdev_fdb

Kernel	Title	Rank 🛈	Repro	Cause bisect	Count	Last	Reported	Patched	Status
upstream	KASAN: slab-use-after-free Read in br_switchdev_fdb_notify bridge	19			2	414d	420d	0/29	auto-obsoleted due to no activity on 2025/09/02 15:50
upstream	KASAN: slab-use-after-free Read in br_switchdev_fdb_notify (2) bridge	19			4	269d	286d	29/29	fixed on 2026/01/22 13:50
upstream	general protection fault in br_switchdev_fdb_notify bridge	2	C	error	82	1812d	1817d	20/29	fixed on 2021/11/10 00:50

================================================================== BUG: KASAN: use-after-free in br_switchdev_fdb_populate net/bridge/br_switchdev.c:142 [inline] BUG: KASAN: use-after-free in br_switchdev_fdb_notify+0x2ad/0x380 net/bridge/br_switchdev.c:163 Read of size 8 at addr ffff8880575f5808 by task kworker/1:3/4256 CPU: 1 PID: 4256 Comm: kworker/1:3 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: events_long br_fdb_cleanup Call Trace: <TASK> dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0xa8/0x210 mm/kasan/report.c:420 kasan_report+0x10b/0x140 mm/kasan/report.c:524 br_switchdev_fdb_populate net/bridge/br_switchdev.c:142 [inline] br_switchdev_fdb_notify+0x2ad/0x380 net/bridge/br_switchdev.c:163 fdb_notify+0x89/0x160 net/bridge/br_fdb.c:189 fdb_delete+0xd52/0x10f0 net/bridge/br_fdb.c:325 br_fdb_cleanup+0x2a3/0x4c0 net/bridge/br_fdb.c:550 process_one_work+0x898/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> Allocated by task 0: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node_track_caller+0xae/0x230 mm/slab_common.c:956 kmalloc_reserve net/core/skbuff.c:446 [inline] __alloc_skb+0x22a/0x7e0 net/core/skbuff.c:515 alloc_skb include/linux/skbuff.h:1271 [inline] __tcp_send_ack+0x9d/0x5a0 net/ipv4/tcp_output.c:4033 tcp_ack_snd_check net/ipv4/tcp_input.c:5672 [inline] tcp_rcv_established+0xeb6/0x1d30 net/ipv4/tcp_input.c:6116 tcp_v4_do_rcv+0x48d/0xb00 net/ipv4/tcp_ipv4.c:1683 tcp_v4_rcv+0x2789/0x2e30 net/ipv4/tcp_ipv4.c:2114 ip_protocol_deliver_rcu+0x3ad/0x780 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2c7/0x510 net/ipv4/ip_input.c:233 NF_HOOK+0x2ff/0x390 include/linux/netfilter.h:302 dst_input include/net/dst.h:463 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:580 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:631 [inline] ip_sublist_rcv+0xa30/0xd10 net/ipv4/ip_input.c:639 ip_list_rcv+0x3df/0x430 net/ipv4/ip_input.c:674 __netif_receive_skb_list_ptype net/core/dev.c:5624 [inline] __netif_receive_skb_list_core+0x574/0x740 net/core/dev.c:5672 __netif_receive_skb_list net/core/dev.c:5724 [inline] netif_receive_skb_list_internal+0x90f/0xc50 net/core/dev.c:5815 gro_normal_list include/net/gro.h:433 [inline] napi_complete_done+0x37d/0x830 net/core/dev.c:6156 virtqueue_napi_complete drivers/net/virtio_net.c:403 [inline] virtnet_poll+0x991/0x1150 drivers/net/virtio_net.c:1717 __napi_poll+0xc0/0x460 net/core/dev.c:6590 napi_poll net/core/dev.c:6657 [inline] net_rx_action+0x5b1/0xad0 net/core/dev.c:6771 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596 __do_softirq kernel/softirq.c:630 [inline] invoke_softirq kernel/softirq.c:470 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691 common_interrupt+0xb5/0xd0 arch/x86/kernel/irq.c:242 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:682 Freed by task 32: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700 skb_free_head net/core/skbuff.c:762 [inline] skb_release_data+0x5db/0x7c0 net/core/skbuff.c:791 skb_release_all net/core/skbuff.c:856 [inline] napi_consume_skb+0x12f/0x1d0 net/core/skbuff.c:1113 free_old_xmit_skbs+0x111/0x2a0 drivers/net/virtio_net.c:1639 virtnet_poll_tx+0x20f/0x520 drivers/net/virtio_net.c:1811 __napi_poll+0xc0/0x460 net/core/dev.c:6590 napi_poll net/core/dev.c:6657 [inline] net_rx_action+0x5b1/0xad0 net/core/dev.c:6771 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596 __do_softirq kernel/softirq.c:630 [inline] invoke_softirq kernel/softirq.c:470 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691 common_interrupt+0xb5/0xd0 arch/x86/kernel/irq.c:242 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:682 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486 call_rcu+0x154/0x980 kernel/rcu/tree.c:2849 br_del_if+0x15d/0x330 net/bridge/br_if.c:739 do_set_master net/core/rtnetlink.c:2616 [inline] do_setlink+0xe3c/0x3c40 net/core/rtnetlink.c:2840 rtnl_group_changelink net/core/rtnetlink.c:3361 [inline] __rtnl_newlink net/core/rtnetlink.c:3618 [inline] rtnl_newlink+0x10a3/0x1ff0 net/core/rtnetlink.c:3655 rtnetlink_rcv_msg+0x79b/0xed0 net/core/rtnetlink.c:6150 netlink_rcv_skb+0x1de/0x420 net/netlink/af_netlink.c:2511 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x89e/0xbc0 net/netlink/af_netlink.c:1872 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x59b/0x970 net/socket.c:2519 ___sys_sendmsg+0x21c/0x290 net/socket.c:2573 __sys_sendmsg net/socket.c:2602 [inline] __do_sys_sendmsg net/socket.c:2611 [inline] __se_sys_sendmsg+0x19e/0x270 net/socket.c:2609 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff8880575f5800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 8 bytes inside of 1024-byte region [ffff8880575f5800, ffff8880575f5c00) The buggy address belongs to the physical page: page:ffffea00015d7c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x575f0 head:ffffea00015d7c00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888017441dc0 raw: 0000000000000000 0000000000100010 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 0x52a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 4273, tgid 4273 (syz-executor), ts 79282216194, free_ts 22688754025 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532 prep_new_page mm/page_alloc.c:2539 [inline] get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614 alloc_slab_page+0x5d/0x160 mm/slub.c:1799 allocate_slab mm/slub.c:1944 [inline] new_slab+0x87/0x2c0 mm/slub.c:1997 ___slab_alloc+0xbc6/0x1230 mm/slub.c:3154 __slab_alloc mm/slub.c:3240 [inline] slab_alloc_node mm/slub.c:3325 [inline] __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398 __do_kmalloc_node mm/slab_common.c:935 [inline] __kmalloc+0xa0/0x240 mm/slab_common.c:949 kmalloc_array include/linux/slab.h:615 [inline] batadv_hash_new+0x77/0x290 net/batman-adv/hash.c:52 batadv_bla_init+0x44b/0x6f0 net/batman-adv/bridge_loop_avoidance.c:1563 batadv_mesh_init+0x3d8/0x700 net/batman-adv/main.c:211 batadv_softif_init_late+0x9b6/0xe50 net/batman-adv/soft-interface.c:810 register_netdevice+0x65b/0x1aa0 net/core/dev.c:10130 rtnl_newlink_create net/core/rtnetlink.c:3422 [inline] __rtnl_newlink net/core/rtnetlink.c:3642 [inline] rtnl_newlink+0x14c4/0x1ff0 net/core/rtnetlink.c:3655 rtnetlink_rcv_msg+0x79b/0xed0 net/core/rtnetlink.c:6150 netlink_rcv_skb+0x1de/0x420 net/netlink/af_netlink.c:2511 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1459 [inline] free_pcp_prepare mm/page_alloc.c:1509 [inline] free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479 free_contig_range+0x9d/0x150 mm/page_alloc.c:9574 destroy_args+0x100/0xa31 mm/debug_vm_pgtable.c:1031 debug_vm_pgtable+0x32a/0x37e mm/debug_vm_pgtable.c:1359 do_one_initcall+0x214/0x7a0 init/main.c:1310 do_initcall_level+0x137/0x1e4 init/main.c:1383 do_initcalls+0x4b/0x8a init/main.c:1399 kernel_init_freeable+0x3fa/0x5ac init/main.c:1638 kernel_init+0x19/0x1b0 init/main.c:1526 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff8880575f5700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880575f5780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880575f5800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880575f5880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880575f5900: 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
2025/12/04 12:44	linux-6.1.y	f6e38ae624cf	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci2-linux-6-1-kasan	KASAN: use-after-free Read in br_switchdev_fdb_notify

Crashes (1):

Assets (help?)