================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1667 [inline] BUG: KASAN: use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:169 [inline] BUG: KASAN: use-after-free in mutex_lock+0x8e/0x1c0 kernel/locking/mutex.c:288 Write of size 8 at addr ffff88811884c150 by task syz.8.648/2734 CPU: 0 PID: 2734 Comm: syz.8.648 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0x10f/0x150 mm/kasan/report.c:444 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1667 [inline] __mutex_trylock_fast kernel/locking/mutex.c:169 [inline] mutex_lock+0x8e/0x1c0 kernel/locking/mutex.c:288 pppol2tp_release+0x178/0x2b0 net/l2tp/l2tp_ppp.c:442 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x200 net/socket.c:1336 __fput+0x22b/0x900 fs/file_table.c:311 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:181 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f70e1dbd0d9 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:00007fffa6c5eb48 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f70e2046da0 RCX: 00007f70e1dbd0d9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f70e2046da0 R08: 0000000000000006 R09: 0000000000000000 R10: 00007f70e2046cb0 R11: 0000000000000246 R12: 0000000000017b41 R13: 00007f70e204509c R14: 00000000000179f1 R15: 00007f70e2045090 Allocated by task 2735: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:433 [inline] ____kasan_kmalloc mm/kasan/common.c:512 [inline] __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:521 kasan_kmalloc include/linux/kasan.h:227 [inline] __kmalloc+0x13d/0x2c0 mm/slub.c:4436 kmalloc include/linux/slab.h:624 [inline] kzalloc include/linux/slab.h:750 [inline] l2tp_session_create+0x39/0xb60 net/l2tp/l2tp_core.c:1616 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:772 __sys_connect_file net/socket.c:1923 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1940 __do_sys_connect net/socket.c:1950 [inline] __se_sys_connect net/socket.c:1947 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:1947 x64_sys_call+0x7c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 2734: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kfree+0xc4/0x270 mm/slub.c:4588 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline] l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193 l2tp_session_delete+0x3a9/0x4a0 net/l2tp/l2tp_core.c:1589 pppol2tp_release+0x169/0x2b0 net/l2tp/l2tp_ppp.c:439 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x200 net/socket.c:1336 __fput+0x22b/0x900 fs/file_table.c:311 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:181 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 __call_rcu_common kernel/rcu/tree.c:3011 [inline] call_rcu+0x10b/0xf60 kernel/rcu/tree.c:3129 pwq_unbound_release_workfn+0x283/0x2c0 kernel/workqueue.c:-1 process_one_work+0x6c8/0xbb0 kernel/workqueue.c:2328 worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475 kthread+0x3f5/0x4f0 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 The buggy address belongs to the object at ffff88811884c000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 336 bytes inside of 512-byte region [ffff88811884c000, ffff88811884c200) The buggy address belongs to the page: page:ffffea0004621300 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11884c head:ffffea0004621300 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 ffffea0004a9c000 0000000200000002 ffff888100042f00 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 674, ts 51366576960, free_ts 51343513050 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1937 [inline] new_slab+0xa0/0x4d0 mm/slub.c:2000 ___slab_alloc+0x3ac/0x840 mm/slub.c:3033 __slab_alloc+0x49/0x90 mm/slub.c:3120 slab_alloc_node mm/slub.c:3211 [inline] slab_alloc mm/slub.c:3255 [inline] __kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4954 kmalloc_reserve net/core/skbuff.c:357 [inline] __alloc_skb+0x210/0x730 net/core/skbuff.c:428 alloc_skb include/linux/skbuff.h:1183 [inline] alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6207 sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2542 unix_dgram_sendmsg+0x6f3/0x19b0 net/unix/af_unix.c:1816 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] sock_write_iter+0x2a6/0x3a0 net/socket.c:1080 call_write_iter include/linux/fs.h:2212 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x831/0xfd0 fs/read_write.c:594 ksys_write+0x14a/0x260 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:656 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1474 [inline] free_pcp_prepare mm/page_alloc.c:1546 [inline] free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536 free_unref_page+0xae/0x540 mm/page_alloc.c:3618 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x6c/0x100 mm/page_alloc.c:5900 free_nonslab_page+0x86/0xc0 mm/slub.c:3564 kfree+0x19a/0x270 mm/slub.c:4585 kvfree+0x35/0x40 mm/util.c:661 bpf_check+0x9ca4/0xf750 kernel/bpf/verifier.c:14242 bpf_prog_load+0x10c5/0x1620 kernel/bpf/syscall.c:2328 __sys_bpf+0x51d/0x7d0 kernel/bpf/syscall.c:4633 __do_sys_bpf kernel/bpf/syscall.c:4737 [inline] __se_sys_bpf kernel/bpf/syscall.c:4735 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:4735 x64_sys_call+0x4b9/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:322 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Memory state around the buggy address: ffff88811884c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811884c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88811884c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811884c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811884c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================