[syzbot] [net?] KASAN: slab-use-after-free Read in udp_tunnel_update_gro_lookup

[syzbot <syzbot+1fb3291cc1beeb3c315a@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    23c9ff659140 Merge branch 'net-stmmac-remove-unnecessary-o..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=109925e4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=aeeec842a6bdc8b9
dashboard link: https://syzkaller.appspot.com/bug?extid=1fb3291cc1beeb3c315a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c325a67439ff/disk-23c9ff65.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7fdb9709d1a6/vmlinux-23c9ff65.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e7d7be5c9841/bzImage-23c9ff65.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1fb3291cc1beeb3c315a@syzkaller.appspotmail.com

netlink: 'syz.2.655': attribute type 39 has an invalid length.
==================================================================
BUG: KASAN: slab-use-after-free in udp_tunnel_update_gro_lookup+0x23c/0x2c0 net/ipv4/udp_offload.c:65
Read of size 8 at addr ffff88801235ebe8 by task syz.2.655/7921

CPU: 1 UID: 0 PID: 7921 Comm: syz.2.655 Not tainted 6.14.0-rc6-syzkaller-01313-g23c9ff659140 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 udp_tunnel_update_gro_lookup+0x23c/0x2c0 net/ipv4/udp_offload.c:65
 sk_common_release+0x71/0x2e0 net/core/sock.c:3896
 inet_release+0x17d/0x200 net/ipv4/af_inet.c:435
 __sock_release net/socket.c:647 [inline]
 sock_release+0x82/0x150 net/socket.c:675
 sock_free drivers/net/wireguard/socket.c:339 [inline]
 wg_socket_reinit+0x215/0x380 drivers/net/wireguard/socket.c:435
 wg_stop+0x59f/0x600 drivers/net/wireguard/device.c:133
 __dev_close_many+0x3a6/0x700 net/core/dev.c:1717
 dev_close_many+0x24e/0x4c0 net/core/dev.c:1742
 unregister_netdevice_many_notify+0x629/0x24f0 net/core/dev.c:11923
 rtnl_delete_link net/core/rtnetlink.c:3512 [inline]
 rtnl_dellink+0x526/0x8c0 net/core/rtnetlink.c:3554
 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6945
 netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f35ab38d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f35ac28f038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f35ab5a6160 RCX: 00007f35ab38d169
RDX: 0000000000000000 RSI: 0000400000000000 RDI: 0000000000000004
RBP: 00007f35ab40e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f35ab5a6160 R15: 00007ffdddd781b8
 </TASK>

Allocated by task 7770:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4115 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4171
 sk_prot_alloc+0x58/0x210 net/core/sock.c:2190
 sk_alloc+0x3e/0x370 net/core/sock.c:2249
 inet_create+0x648/0xea0 net/ipv4/af_inet.c:326
 __sock_create+0x4c0/0xa30 net/socket.c:1539
 sock_create net/socket.c:1597 [inline]
 __sys_socket_create net/socket.c:1634 [inline]
 __sys_socket+0x150/0x3c0 net/socket.c:1681
 __do_sys_socket net/socket.c:1695 [inline]
 __se_sys_socket net/socket.c:1693 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1693
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 7768:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2353 [inline]
 slab_free mm/slub.c:4609 [inline]
 kmem_cache_free+0x195/0x410 mm/slub.c:4711
 sk_prot_free net/core/sock.c:2230 [inline]
 __sk_destruct+0x4fd/0x690 net/core/sock.c:2327
 inet_release+0x17d/0x200 net/ipv4/af_inet.c:435
 __sock_release net/socket.c:647 [inline]
 sock_close+0xbc/0x240 net/socket.c:1389
 __fput+0x3e9/0x9f0 fs/file_table.c:464
 task_work_run+0x24f/0x310 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88801235e4c0
 which belongs to the cache UDP of size 1856
The buggy address is located 1832 bytes inside of
 freed 1856-byte region [ffff88801235e4c0, ffff88801235ec00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88801235be00 pfn:0x12358
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88802f542d01
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff888023294780 dead000000000122 0000000000000000
raw: ffff88801235be00 000000008010000c 00000000f5000000 ffff88802f542d01
head: 00fff00000000040 ffff888023294780 dead000000000122 0000000000000000
head: ffff88801235be00 000000008010000c 00000000f5000000 ffff88802f542d01
head: 00fff00000000003 ffffea000048d601 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 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 5831, tgid 5831 (syz-executor), ts 69973022954, free_ts 69950034125
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4740
 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2423 [inline]
 allocate_slab+0x8f/0x3a0 mm/slub.c:2587
 new_slab mm/slub.c:2640 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
 __slab_alloc+0x58/0xa0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 kmem_cache_alloc_noprof+0x268/0x380 mm/slub.c:4171
 sk_prot_alloc+0x58/0x210 net/core/sock.c:2190
 sk_alloc+0x3e/0x370 net/core/sock.c:2249
 inet_create+0x648/0xea0 net/ipv4/af_inet.c:326
 __sock_create+0x4c0/0xa30 net/socket.c:1539
 udp_sock_create4+0xda/0x670 net/ipv4/udp_tunnel_core.c:18
 udp_sock_create include/net/udp_tunnel.h:59 [inline]
 geneve_create_sock drivers/net/geneve.c:487 [inline]
 geneve_socket_create drivers/net/geneve.c:600 [inline]
 geneve_sock_add+0x469/0xc40 drivers/net/geneve.c:687
 geneve_open+0xe3/0x160 drivers/net/geneve.c:729
 __dev_open+0x45a/0x8a0 net/core/dev.c:1644
page last free pid 5832 tgid 5832 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0xe0d/0x10e0 mm/page_alloc.c:2660
 discard_slab mm/slub.c:2684 [inline]
 __put_partials+0x160/0x1c0 mm/slub.c:3153
 put_cpu_partial+0x17c/0x250 mm/slub.c:3228
 __slab_free+0x290/0x380 mm/slub.c:4479
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4115 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4171
 getname_kernel+0x59/0x2f0 fs/namei.c:250
 kern_path+0x1d/0x50 fs/namei.c:2772
 do_loopback+0xc9/0x4f0 fs/namespace.c:2817
 do_mount fs/namespace.c:3900 [inline]
 __do_sys_mount fs/namespace.c:4111 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4088
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88801235ea80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801235eb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801235eb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff88801235ec00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801235ec80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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