ci2 starts bisection 2025-06-23 05:25:18.455313031 +0000 UTC m=+185434.798679360 bisecting fixing commit since 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d building syzkaller on 1a5d9317ecfa21e32cf9c876306c7b5f665999bf ensuring issue is reproducible on original commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: d28cc2de318655da176ac2b8a939c481351e4deffe1ac7f375db2456d782c947 all runs: crashed: KASAN: use-after-free Write in l2tp_session_delete representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] check whether we can drop unnecessary instrumentation disabling configs for [HANG LEAK UBSAN BUG LOCKDEP ATOMIC_SLEEP], they are not needed testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: 998fa447218b11ebeae7ecdd786d5d2c4cabfcbf9c020c345b974a1231f31c16 all runs: crashed: KASAN: use-after-free Write in l2tp_session_delete representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] the bug reproduces without the instrumentation disabling configs for [LOCKDEP ATOMIC_SLEEP HANG LEAK UBSAN BUG], they are not needed kconfig minimization: base=4921 full=6215 leaves diff=255 split chunks (needed=false): <255> split chunk #0 of len 255 into 5 parts testing without sub-chunk 1/5 disabling configs for [ATOMIC_SLEEP HANG LEAK UBSAN BUG LOCKDEP], they are not needed testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: c4978f7a54703e3b1417e6e283e84d6cbaba2203ce3f091aa319e8e8cef01ec0 all runs: crashed: KASAN: use-after-free Write in l2tp_session_delete representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] the chunk can be dropped testing without sub-chunk 2/5 disabling configs for [HANG LEAK UBSAN BUG LOCKDEP ATOMIC_SLEEP], they are not needed testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: fc61d91a54b76ad11c8dd2cbb1f762d0ef0a524e242fccfdd21e5f7cc96f36cd run #0: crashed: KASAN: use-after-free Write in l2tp_session_delete run #1: crashed: KASAN: use-after-free Write in l2tp_session_delete run #2: crashed: KASAN: use-after-free Write in l2tp_session_delete run #3: crashed: KASAN: use-after-free Write in l2tp_session_delete run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] the chunk can be dropped testing without sub-chunk 3/5 disabling configs for [LEAK UBSAN BUG LOCKDEP ATOMIC_SLEEP HANG], they are not needed testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: 40b049a371359dd5f0f9d0d929a20f8e594039573e7c4440cd06cc1ca8bddb3c run #0: crashed: KASAN: use-after-free Write in l2tp_session_delete run #1: crashed: KASAN: use-after-free Write in l2tp_session_delete run #2: crashed: KASAN: use-after-free Write in l2tp_session_delete run #3: crashed: KASAN: use-after-free Write in l2tp_session_delete run #4: crashed: KASAN: use-after-free Write in l2tp_session_delete run #5: crashed: KASAN: use-after-free Write in l2tp_session_delete run #6: crashed: KASAN: use-after-free Write in l2tp_session_delete run #7: crashed: KASAN: use-after-free Write in l2tp_session_delete run #8: crashed: KASAN: use-after-free Write in l2tp_session_delete run #9: crashed: KASAN: use-after-free Write in l2tp_session_delete run #10: crashed: KASAN: use-after-free Write in l2tp_session_delete run #11: crashed: KASAN: use-after-free Write in l2tp_session_delete run #12: crashed: KASAN: use-after-free Write in l2tp_session_delete run #13: crashed: KASAN: use-after-free Write in l2tp_session_delete run #14: crashed: KASAN: use-after-free Write in l2tp_session_delete run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] the chunk can be dropped testing without sub-chunk 4/5 disabling configs for [UBSAN BUG LOCKDEP ATOMIC_SLEEP HANG LEAK], they are not needed testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: 665dbbe35afead65a7f72a612760638ad84e77dffc8ecda220abc91927f3c027 run #0: crashed: KASAN: use-after-free Write in l2tp_session_delete run #1: crashed: KASAN: use-after-free Write in l2tp_session_delete run #2: crashed: KASAN: use-after-free Write in l2tp_session_delete run #3: crashed: KASAN: use-after-free Write in l2tp_session_delete run #4: crashed: KASAN: use-after-free Write in l2tp_session_delete run #5: crashed: KASAN: use-after-free Write in l2tp_session_delete run #6: crashed: KASAN: use-after-free Write in l2tp_session_delete run #7: crashed: KASAN: use-after-free Write in l2tp_session_delete run #8: crashed: KASAN: use-after-free Write in l2tp_session_delete run #9: OK run #10: crashed: KASAN: use-after-free Write in l2tp_session_delete run #11: OK run #12: OK run #13: OK run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] the chunk can be dropped testing without sub-chunk 5/5 disabling configs for [ATOMIC_SLEEP HANG LEAK UBSAN BUG LOCKDEP], they are not needed testing commit 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 failed building 7d1f9b5c2ff516f9c97fffe9613799b29ef4946d: net/socket.c:1191: undefined reference to `wext_handle_ioctl' net/socket.c:3390: undefined reference to `compat_wext_handle_ioctl' net/core/net-procfs.c:343: undefined reference to `wext_proc_exit' net/core/net-procfs.c:327: undefined reference to `wext_proc_init' minimized to 51 configs; suspects: [HID_ZEROPLUS USB_MON USB_NET_CDC_MBIM USB_NET_CDC_SUBSET USB_NET_CDC_SUBSET_ENABLE USB_NET_DM9601 USB_NET_GL620A USB_NET_MCS7830 USB_NET_NET1080 USB_NET_PLUSB USB_NET_RNDIS_HOST USB_NET_SMSC75XX USB_NET_SMSC95XX USB_NET_SR9700 USB_NET_SR9800 USB_NET_ZAURUS USB_OHCI_HCD USB_OHCI_HCD_PCI USB_OHCI_HCD_PLATFORM USB_OTG USB_OTG_FSM USB_PRINTER USB_SERIAL USB_SERIAL_FTDI_SIO USB_SERIAL_GENERIC USB_SERIAL_PL2303 USB_STORAGE_ALAUDA USB_STORAGE_CYPRESS_ATACB USB_STORAGE_DATAFAB USB_STORAGE_FREECOM USB_STORAGE_ISD200 USB_STORAGE_JUMPSHOT USB_STORAGE_KARMA USB_STORAGE_ONETOUCH USB_STORAGE_SDDR09 USB_STORAGE_SDDR55 USB_STORAGE_USBAT USB_TRANCEVIBRATOR USB_U_AUDIO USB_U_ETHER USB_U_SERIAL USB_WDM USB_XHCI_PCI_RENESAS WLAN WLAN_VENDOR_ATH WLAN_VENDOR_ATMEL WLAN_VENDOR_BROADCOM WLAN_VENDOR_INTERSIL WLAN_VENDOR_MARVELL WLAN_VENDOR_MEDIATEK WLAN_VENDOR_MICROCHIP WLAN_VENDOR_RALINK WLAN_VENDOR_REALTEK WLAN_VENDOR_RSI WLAN_VENDOR_ZYDAS X86_X32 ZEROPLUS_FF] disabling configs for [ATOMIC_SLEEP HANG LEAK UBSAN BUG LOCKDEP], they are not needed testing current HEAD e678c93d43cc59dbad86bb0ad0ff6a7ed675a154 testing commit e678c93d43cc59dbad86bb0ad0ff6a7ed675a154 gcc compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.40 kernel signature: d342c626bf9d2329a09527083c283304439ad2849e5c096f390de2f443d8a10d run #0: crashed: KASAN: use-after-free Write in l2tp_session_delete run #1: crashed: KASAN: use-after-free Write in l2tp_session_delete run #2: crashed: KASAN: use-after-free Write in l2tp_session_delete run #3: crashed: KASAN: use-after-free Write in l2tp_session_delete run #4: crashed: KASAN: use-after-free Write in l2tp_session_delete run #5: crashed: KASAN: use-after-free Write in l2tp_session_delete run #6: crashed: KASAN: use-after-free Write in l2tp_session_delete run #7: crashed: KASAN: use-after-free Write in l2tp_session_delete run #8: crashed: KASAN: use-after-free Write in l2tp_session_delete run #9: crashed: KASAN: use-after-free Write in l2tp_session_delete run #10: crashed: KASAN: use-after-free Write in l2tp_session_delete run #11: crashed: KASAN: use-after-free Write in l2tp_session_delete run #12: crashed: KASAN: use-after-free Write in l2tp_session_delete run #13: crashed: KASAN: use-after-free Write in l2tp_session_delete run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK representative crash: KASAN: use-after-free Write in l2tp_session_delete, types: [KASAN] crash still not fixed/happens on the oldest tested release reproducer is flaky (0.50 repro chance estimate) revisions tested: 7, total time: 2h21m30.526959796s (build: 20m41.832586741s, test: 1h52m15.333080253s) crash still not fixed or there were kernel test errors commit msg: Revert "coredump: hand a pidfd to the usermode coredump helper" crash: KASAN: use-after-free Write in l2tp_session_delete ================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:70 [inline] BUG: KASAN: use-after-free in l2tp_session_delete+0x1e/0x440 net/l2tp/l2tp_core.c:1563 Write of size 8 at addr ffff88811efbd808 by task kworker/u4:5/481 CPU: 0 PID: 481 Comm: kworker/u4:5 Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: l2tp l2tp_tunnel_del_work Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x38/0x49 lib/dump_stack.c:106 print_address_description.constprop.0+0x24/0x160 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report.cold+0x82/0xdb mm/kasan/report.c:444 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x148/0x190 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] test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:70 [inline] l2tp_session_delete+0x1e/0x440 net/l2tp/l2tp_core.c:1563 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1218 [inline] l2tp_tunnel_del_work+0x182/0x400 net/l2tp/l2tp_core.c:1258 process_one_work+0x62c/0xec0 kernel/workqueue.c:2325 worker_thread+0x48e/0xdb0 kernel/workqueue.c:2472 kthread+0x324/0x3e0 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Allocated by task 3394: kasan_save_stack+0x26/0x50 mm/kasan/common.c:38 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 mm/kasan/common.c:471 [inline] __kasan_kmalloc+0xae/0xe0 mm/kasan/common.c:521 kasan_kmalloc include/linux/kasan.h:227 [inline] __kmalloc+0x2e6/0x550 mm/slub.c:4431 kmalloc include/linux/slab.h:621 [inline] kzalloc include/linux/slab.h:747 [inline] l2tp_session_create+0x38/0xa80 net/l2tp/l2tp_core.c:1599 pppol2tp_connect+0xe03/0x1910 net/l2tp/l2tp_ppp.c:782 __sys_connect_file+0x136/0x190 net/socket.c:1923 __sys_connect+0x101/0x130 net/socket.c:1940 __do_sys_connect net/socket.c:1950 [inline] __se_sys_connect net/socket.c:1947 [inline] __x64_sys_connect+0x6e/0xb0 net/socket.c:1947 x64_sys_call+0x85c/0x990 arch/x86/include/generated/asm/syscalls_64.h:43 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 24: kasan_save_stack+0x26/0x50 mm/kasan/common.c:38 kasan_set_track+0x25/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x24/0x40 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:365 [inline] ____kasan_slab_free mm/kasan/common.c:327 [inline] __kasan_slab_free+0x111/0x150 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook+0x94/0x1a0 mm/slub.c:1749 slab_free mm/slub.c:3521 [inline] kfree+0xc2/0x2a0 mm/slub.c:4583 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline] l2tp_session_dec_refcount+0x7a/0x130 net/l2tp/l2tp_core.c:205 pppol2tp_session_destruct+0xa3/0xd0 net/l2tp/l2tp_ppp.c:419 __sk_destruct+0x42/0x520 net/core/sock.c:1962 sk_destruct+0x9b/0xc0 net/core/sock.c:2007 __sk_free+0xd1/0x350 net/core/sock.c:2018 sk_free+0x45/0x60 net/core/sock.c:2029 sock_put include/net/sock.h:1939 [inline] pppol2tp_put_sk+0x66/0x90 net/l2tp/l2tp_ppp.c:402 rcu_do_batch+0x340/0xca0 kernel/rcu/tree.c:2523 rcu_core+0x56b/0xac0 kernel/rcu/tree.c:2763 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2776 handle_softirqs+0x1c5/0x510 kernel/softirq.c:583 run_ksoftirqd kernel/softirq.c:959 [inline] run_ksoftirqd+0x2b/0x40 kernel/softirq.c:951 smpboot_thread_fn+0x502/0x7b0 kernel/smpboot.c:164 kthread+0x324/0x3e0 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Last potentially related work creation: kasan_save_stack+0x26/0x50 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd8/0xf0 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 __call_rcu_common.constprop.0+0xd7/0x11b0 kernel/rcu/tree.c:3007 call_rcu+0x9/0x10 kernel/rcu/tree.c:3125 pppol2tp_release+0x292/0x3e0 net/l2tp/l2tp_ppp.c:458 __sock_release+0xc2/0x270 net/socket.c:649 sock_close+0x10/0x20 net/socket.c:1336 __fput+0x319/0x960 fs/file_table.c:311 ____fput+0x9/0x10 fs/file_table.c:339 task_work_run+0xc2/0x150 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:181 [inline] exit_to_user_mode_prepare+0x143/0x150 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x21/0x40 kernel/entry/common.c:307 do_syscall_64+0x40/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 The buggy address belongs to the object at ffff88811efbd800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 8 bytes inside of 512-byte region [ffff88811efbd800, ffff88811efbda00) The buggy address belongs to the page: page:ffffea00047bef00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11efbc head:ffffea00047bef00 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 dead000000000100 dead000000000122 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 491, ts 71767757178, free_ts 41543953841 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook mm/page_alloc.c:2605 [inline] prep_new_page+0x1a2/0x310 mm/page_alloc.c:2611 get_page_from_freelist+0x1ce2/0x30a0 mm/page_alloc.c:4485 __alloc_pages+0x2d5/0x26f0 mm/page_alloc.c:5789 __alloc_pages_node include/linux/gfp.h:591 [inline] alloc_pages_node include/linux/gfp.h:605 [inline] alloc_pages include/linux/gfp.h:618 [inline] alloc_slab_page mm/slub.c:1793 [inline] allocate_slab+0x39d/0x530 mm/slub.c:1932 new_slab mm/slub.c:1995 [inline] ___slab_alloc.constprop.0+0x3ca/0x890 mm/slub.c:3028 __slab_alloc.constprop.0+0x42/0x80 mm/slub.c:3115 slab_alloc_node mm/slub.c:3206 [inline] slab_alloc mm/slub.c:3250 [inline] __kmalloc_track_caller+0x501/0x540 mm/slub.c:4949 kmalloc_reserve net/core/skbuff.c:357 [inline] __alloc_skb+0x8b/0x250 net/core/skbuff.c:428 alloc_skb include/linux/skbuff.h:1183 [inline] nlmsg_new include/net/netlink.h:953 [inline] netlink_ack+0x134/0xa00 net/netlink/af_netlink.c:2428 netlink_rcv_skb+0x27a/0x3c0 net/netlink/af_netlink.c:2499 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:5668 netlink_unicast_kernel net/netlink/af_netlink.c:1315 [inline] netlink_unicast+0x4f8/0x810 net/netlink/af_netlink.c:1341 netlink_sendmsg+0x810/0xd10 net/netlink/af_netlink.c:1909 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg+0xb5/0xf0 net/socket.c:716 __sys_sendto+0x1e3/0x2f0 net/socket.c:2063 __do_sys_sendto net/socket.c:2075 [inline] __se_sys_sendto net/socket.c:2071 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:2071 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1472 [inline] free_pcp_prepare+0x1b6/0x4c0 mm/page_alloc.c:1544 free_unref_page_prepare mm/page_alloc.c:3534 [inline] free_unref_page+0x84/0x760 mm/page_alloc.c:3616 __put_single_page mm/swap.c:98 [inline] __put_page+0xdb/0x110 mm/swap.c:129 put_page include/linux/mm.h:1295 [inline] anon_pipe_buf_release+0x128/0x1a0 fs/pipe.c:137 pipe_buf_release include/linux/pipe_fs_i.h:219 [inline] pipe_read+0x574/0xdf0 fs/pipe.c:323 call_read_iter include/linux/fs.h:2198 [inline] new_sync_read+0x489/0x6d0 fs/read_write.c:404 vfs_read+0x34a/0x4b0 fs/read_write.c:485 ksys_read+0x192/0x210 fs/read_write.c:623 __do_sys_read fs/read_write.c:633 [inline] __se_sys_read fs/read_write.c:631 [inline] __x64_sys_read+0x6e/0xb0 fs/read_write.c:631 x64_sys_call+0x982/0x990 arch/x86/include/generated/asm/syscalls_64.h:1 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x33/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Memory state around the buggy address: ffff88811efbd700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88811efbd780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88811efbd800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811efbd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811efbd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================