================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline] BUG: KASAN: use-after-free in enqueue_timer+0xb7/0x300 kernel/time/timer.c:541 Write of size 8 at addr ffff8881f083b1c8 by task syz.3.709/2810 CPU: 0 PID: 2810 Comm: syz.3.709 Not tainted 5.4.290-syzkaller-00017-g6b07fcd94a6a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x241 lib/dump_stack.c:118 print_address_description+0x8c/0x600 mm/kasan/report.c:384 __kasan_report+0xf3/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 hlist_add_head include/linux/list.h:814 [inline] enqueue_timer+0xb7/0x300 kernel/time/timer.c:541 __internal_add_timer kernel/time/timer.c:554 [inline] internal_add_timer+0x240/0x430 kernel/time/timer.c:604 __mod_timer+0x6f1/0x13e0 kernel/time/timer.c:1065 tun_flow_init drivers/net/tun.c:1446 [inline] tun_net_init+0x287/0x540 drivers/net/tun.c:1055 register_netdevice+0x1c0/0x12a0 net/core/dev.c:9139 tun_set_iff+0x7f7/0xdc0 drivers/net/tun.c:2922 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3187 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7f0bd3933169 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:00007f0bd1f9d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f0bd3b4bfa0 RCX: 00007f0bd3933169 RDX: 0000400000000080 RSI: 00000000400454ca RDI: 0000000000000003 RBP: 00007f0bd39b42a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f0bd3b4bfa0 R15: 00007fffe025c7e8 Allocated by task 2794: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc_track_caller+0x100/0x2b0 mm/slub.c:4449 __kmalloc_reserve net/core/skbuff.c:142 [inline] pskb_expand_head+0x10c/0x10b0 net/core/skbuff.c:1653 __skb_cow include/linux/skbuff.h:3208 [inline] skb_cow_head include/linux/skbuff.h:3242 [inline] ip_tunnel_xmit+0x1636/0x2690 net/ipv4/ip_tunnel.c:822 __gre_xmit net/ipv4/ip_gre.c:465 [inline] ipgre_xmit+0x79f/0xb30 net/ipv4/ip_gre.c:660 __netdev_start_xmit include/linux/netdevice.h:4538 [inline] netdev_start_xmit include/linux/netdevice.h:4552 [inline] xmit_one net/core/dev.c:3221 [inline] dev_hard_start_xmit+0x1b7/0x6b0 net/core/dev.c:3237 __dev_queue_xmit+0x138c/0x2790 net/core/dev.c:3821 __bpf_tx_skb net/core/filter.c:2063 [inline] __bpf_redirect_no_mac net/core/filter.c:2097 [inline] __bpf_redirect+0x78f/0xe20 net/core/filter.c:2120 ____bpf_clone_redirect net/core/filter.c:2151 [inline] bpf_clone_redirect+0x249/0x350 net/core/filter.c:2123 bpf_prog_208b094576c80b22+0x5ff/0x1000 bpf_call_func include/linux/filter.h:627 [inline] bpf_test_run+0x2ae/0x6c0 net/bpf/test_run.c:44 bpf_prog_test_run_skb+0x73c/0xf00 net/bpf/test_run.c:311 bpf_prog_test_run kernel/bpf/syscall.c:2124 [inline] __do_sys_bpf kernel/bpf/syscall.c:2909 [inline] __se_sys_bpf+0x2e37/0xbcb0 kernel/bpf/syscall.c:2849 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 2794: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] kasan_set_free_info mm/kasan/common.c:345 [inline] __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook mm/slub.c:1494 [inline] slab_free mm/slub.c:3080 [inline] kfree+0x123/0x370 mm/slub.c:4071 skb_release_all net/core/skbuff.c:675 [inline] __kfree_skb net/core/skbuff.c:689 [inline] kfree_skb+0xb8/0x3c0 net/core/skbuff.c:708 ip_mc_output+0x444/0xa70 net/ipv4/ip_output.c:412 iptunnel_xmit+0x476/0x850 net/ipv4/ip_tunnel_core.c:78 ip_tunnel_xmit+0x1ac0/0x2690 net/ipv4/ip_tunnel.c:831 __gre_xmit net/ipv4/ip_gre.c:465 [inline] ipgre_xmit+0x79f/0xb30 net/ipv4/ip_gre.c:660 __netdev_start_xmit include/linux/netdevice.h:4538 [inline] netdev_start_xmit include/linux/netdevice.h:4552 [inline] xmit_one net/core/dev.c:3221 [inline] dev_hard_start_xmit+0x1b7/0x6b0 net/core/dev.c:3237 __dev_queue_xmit+0x138c/0x2790 net/core/dev.c:3821 __bpf_tx_skb net/core/filter.c:2063 [inline] __bpf_redirect_no_mac net/core/filter.c:2097 [inline] __bpf_redirect+0x78f/0xe20 net/core/filter.c:2120 ____bpf_clone_redirect net/core/filter.c:2151 [inline] bpf_clone_redirect+0x249/0x350 net/core/filter.c:2123 bpf_prog_208b094576c80b22+0x5ff/0x1000 bpf_call_func include/linux/filter.h:627 [inline] bpf_test_run+0x2ae/0x6c0 net/bpf/test_run.c:44 bpf_prog_test_run_skb+0x73c/0xf00 net/bpf/test_run.c:311 bpf_prog_test_run kernel/bpf/syscall.c:2124 [inline] __do_sys_bpf kernel/bpf/syscall.c:2909 [inline] __se_sys_bpf+0x2e37/0xbcb0 kernel/bpf/syscall.c:2849 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 The buggy address belongs to the object at ffff8881f083b000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 456 bytes inside of 1024-byte region [ffff8881f083b000, ffff8881f083b400) The buggy address belongs to the page: page:ffffea0007c20e00 refcount:1 mapcount:0 mapping:ffff8881f5c02280 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c02280 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 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x18f/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4893 alloc_slab_page+0x39/0x3c0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x97/0x440 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x2fe/0x490 mm/slub.c:2667 __slab_alloc+0x62/0xa0 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc_track_caller+0x16d/0x2b0 mm/slub.c:4449 __kmalloc_reserve net/core/skbuff.c:142 [inline] pskb_expand_head+0x10c/0x10b0 net/core/skbuff.c:1653 __skb_cow include/linux/skbuff.h:3208 [inline] skb_cow_head include/linux/skbuff.h:3242 [inline] ip_tunnel_xmit+0x1636/0x2690 net/ipv4/ip_tunnel.c:822 __gre_xmit net/ipv4/ip_gre.c:465 [inline] ipgre_xmit+0x79f/0xb30 net/ipv4/ip_gre.c:660 __netdev_start_xmit include/linux/netdevice.h:4538 [inline] netdev_start_xmit include/linux/netdevice.h:4552 [inline] xmit_one net/core/dev.c:3221 [inline] dev_hard_start_xmit+0x1b7/0x6b0 net/core/dev.c:3237 __dev_queue_xmit+0x138c/0x2790 net/core/dev.c:3821 __bpf_tx_skb net/core/filter.c:2063 [inline] __bpf_redirect_no_mac net/core/filter.c:2097 [inline] __bpf_redirect+0x78f/0xe20 net/core/filter.c:2120 ____bpf_clone_redirect net/core/filter.c:2151 [inline] bpf_clone_redirect+0x249/0x350 net/core/filter.c:2123 bpf_prog_208b094576c80b22+0x5ff/0x1000 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1176 [inline] __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4955 [inline] __free_pages+0x91/0x140 mm/page_alloc.c:4961 device_release+0x6b/0x190 drivers/base/core.c:1776 kobject_cleanup lib/kobject.c:716 [inline] kobject_release lib/kobject.c:747 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1e6/0x2f0 lib/kobject.c:764 tun_set_iff+0x870/0xdc0 drivers/net/tun.c:2924 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3187 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Memory state around the buggy address: ffff8881f083b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881f083b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881f083b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881f083b200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881f083b280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================