syzbot

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BUG: KASAN: use-after-free in br_multicast_rport_from_node net/bridge/br_multicast.c:3124 [inline]
BUG: KASAN: use-after-free in br_multicast_get_rport_slot net/bridge/br_multicast.c:3138 [inline]
BUG: KASAN: use-after-free in br_multicast_add_router+0x168/0x5e0 net/bridge/br_multicast.c:3176
Read of size 8 at addr ffff88802ef461b0 by task syz.1.6265/23550

CPU: 0 PID: 23550 Comm: syz.1.6265 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e 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_multicast_rport_from_node net/bridge/br_multicast.c:3124 [inline]
 br_multicast_get_rport_slot net/bridge/br_multicast.c:3138 [inline]
 br_multicast_add_router+0x168/0x5e0 net/bridge/br_multicast.c:3176
 br_ip4_multicast_add_router net/bridge/br_multicast.c:3200 [inline]
 br_multicast_set_port_router+0x38e/0xce0 net/bridge/br_multicast.c:4387
 br_setport+0xae0/0x10e0 net/bridge/br_netlink.c:986
 br_port_slave_changelink+0x135/0x150 net/bridge/br_netlink.c:1159
 __rtnl_newlink net/core/rtnetlink.c:3607 [inline]
 rtnl_newlink+0x1524/0x1f90 net/core/rtnetlink.c:3661
 rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6158
 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbc5459de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc554eb028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbc54825fa0 RCX: 00007fbc5459de59
RDX: 00000000040040d4 RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007fbc54633e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc54826038 R14: 00007fbc54825fa0 R15: 00007ffeb269d058
 </TASK>

Allocated by task 23147:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc_node_track_caller+0xb0/0x240 mm/slab_common.c:956
 kmalloc_reserve net/core/skbuff.c:446 [inline]
 __alloc_skb+0x226/0x7d0 net/core/skbuff.c:515
 __pskb_copy_fclone+0xaa/0x1130 net/core/skbuff.c:1771
 __pskb_copy include/linux/skbuff.h:1367 [inline]
 pskb_copy include/linux/skbuff.h:3605 [inline]
 tipc_clone_to_loopback+0x102/0x4b0 net/tipc/bearer.c:772
 tipc_loopback_trace net/tipc/bearer.h:256 [inline]
 tipc_node_xmit+0xdda/0xfc0 net/tipc/node.c:1701
 __tipc_sendmsg+0x1d17/0x2c00 net/tipc/socket.c:1515
 tipc_sendmsg+0x51/0x70 net/tipc/socket.c:1403
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmmsg+0x2c3/0x510 net/socket.c:2659
 __do_sys_sendmmsg net/socket.c:2688 [inline]
 __se_sys_sendmmsg net/socket.c:2685 [inline]
 __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x14f/0x950 kernel/rcu/tree.c:2849
 br_del_if+0x15d/0x330 net/bridge/br_if.c:740
 do_set_master net/core/rtnetlink.c:2620 [inline]
 do_setlink+0xdf1/0x29c0 net/core/rtnetlink.c:2844
 __rtnl_newlink net/core/rtnetlink.c:3614 [inline]
 rtnl_newlink+0x16e4/0x1f90 net/core/rtnetlink.c:3661
 rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6158
 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88802ef46000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 432 bytes inside of
 1024-byte region [ffff88802ef46000, ffff88802ef46400)

The buggy address belongs to the physical page:
page:ffffea0000bbd000 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802ef43800 pfn:0x2ef40
head:ffffea0000bbd000 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0000a8fc08 ffffea00009dd808 ffff888017441dc0
raw: ffff88802ef43800 0000000000100008 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 3997, tgid 3997 (dhcpcd-run-hook), ts 47526548511, free_ts 47435375690
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560
 prep_new_page mm/page_alloc.c:2567 [inline]
 get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658
 alloc_slab_page+0x5d/0x180 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:1997
 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc+0xa3/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 load_elf_phdrs fs/binfmt_elf.c:507 [inline]
 load_elf_binary+0x26e/0x2820 fs/binfmt_elf.c:887
 search_binary_handler fs/exec.c:1764 [inline]
 exec_binprm fs/exec.c:1805 [inline]
 bprm_execve+0xaf7/0x17e0 fs/exec.c:1874
 do_execveat_common+0x501/0x6b0 fs/exec.c:1979
 do_execve fs/exec.c:2053 [inline]
 __do_sys_execve fs/exec.c:2129 [inline]
 __se_sys_execve fs/exec.c:2124 [inline]
 __x64_sys_execve+0x8e/0xa0 fs/exec.c:2124
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1487 [inline]
 free_pcp_prepare mm/page_alloc.c:1537 [inline]
 free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509
 free_slab mm/slub.c:2036 [inline]
 discard_slab mm/slub.c:2042 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2591
 put_cpu_partial+0x17c/0x250 mm/slub.c:2667
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x18b/0x2f0 mm/slub.c:3383
 vm_area_alloc+0x20/0xe0 kernel/fork.c:460
 __mmap_region mm/mmap.c:2753 [inline]
 mmap_region+0xcbc/0x1c50 mm/mmap.c:2916
 do_mmap+0x9ce/0x10d0 mm/mmap.c:1436
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:520
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88802ef46080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802ef46100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802ef46180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88802ef46200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802ef46280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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