bisecting fixing commit since 14b58326976de6ef3998eefec1dd7f8b38b97a75 building syzkaller on f721e4a097714a9054b9fe1aadf427afbbd2c157 testing commit 14b58326976de6ef3998eefec1dd7f8b38b97a75 with gcc (GCC) 8.4.1 20210217 kernel signature: 4f0d66ca6794b94e3944a0fc0a4c63ea2331e33d1130982f93673b54cce1655b run #0: crashed: KASAN: use-after-free Read in lock_sock_nested run #1: crashed: KASAN: use-after-free Read in lock_sock_nested run #2: crashed: KASAN: use-after-free Read in lock_sock_nested run #3: crashed: KASAN: use-after-free Read in lock_sock_nested run #4: crashed: KASAN: use-after-free Read in lock_sock_nested run #5: crashed: KASAN: use-after-free Read in lock_sock_nested run #6: crashed: KASAN: use-after-free Read in lock_sock_nested run #7: crashed: KASAN: use-after-free Read in lock_sock_nested run #8: crashed: KASAN: use-after-free Read in lock_sock_nested run #9: crashed: KASAN: use-after-free Read in lock_sock_nested run #10: crashed: KASAN: use-after-free Read in lock_sock_nested run #11: crashed: INFO: trying to register non-static key in l2cap_sock_teardown_cb run #12: crashed: KASAN: use-after-free Read in lock_sock_nested run #13: crashed: KASAN: use-after-free Read in lock_sock_nested run #14: crashed: KASAN: use-after-free Read in lock_sock_nested run #15: crashed: KASAN: use-after-free Read in lock_sock_nested run #16: crashed: KASAN: use-after-free Read in lock_sock_nested run #17: crashed: KASAN: use-after-free Read in lock_sock_nested run #18: crashed: KASAN: use-after-free Read in lock_sock_nested run #19: crashed: KASAN: use-after-free Read in lock_sock_nested testing current HEAD 670d6552eda8ff0c5f396d3d6f0174237917c66c testing commit 670d6552eda8ff0c5f396d3d6f0174237917c66c with gcc (GCC) 8.4.1 20210217 kernel signature: 19a2f1cfec29219b1229070b0f2b26dbad1c60a8bd5662d159844596aa140933 all runs: crashed: KASAN: use-after-free Read in lock_sock_nested revisions tested: 2, total time: 24m14.406501446s (build: 14m58.809911299s, test: 8m46.607659519s) the crash still happens on HEAD commit msg: Linux 4.14.227 crash: KASAN: use-after-free Read in lock_sock_nested hrtimer: interrupt took 82135 ns ================================================================== BUG: KASAN: use-after-free in __lock_acquire+0x2cf0/0x42d0 kernel/locking/lockdep.c:3369 Read of size 8 at addr ffff8881df70af20 by task kworker/0:4/7004 CPU: 0 PID: 7004 Comm: kworker/0:4 Not tainted 4.14.227-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events l2cap_chan_timeout Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:393 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 __lock_acquire+0x2cf0/0x42d0 kernel/locking/lockdep.c:3369 lock_acquire+0x17e/0x3e0 kernel/locking/lockdep.c:3998 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:176 spin_lock_bh include/linux/spinlock.h:322 [inline] lock_sock_nested+0x3a/0x100 net/core/sock.c:2788 l2cap_sock_teardown_cb+0x7a/0x3e0 net/bluetooth/l2cap_sock.c:1341 l2cap_chan_close+0x3be/0x7e0 net/bluetooth/l2cap_core.c:761 l2cap_chan_timeout+0x10e/0x1b0 net/bluetooth/l2cap_core.c:430 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Allocated by task 9096: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc+0x15d/0x410 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] sk_prot_alloc+0x196/0x240 net/core/sock.c:1467 sk_alloc+0x34/0xc20 net/core/sock.c:1521 l2cap_sock_alloc.constprop.4+0x28/0x1e0 net/bluetooth/l2cap_sock.c:1618 l2cap_sock_create+0xb5/0x180 net/bluetooth/l2cap_sock.c:1664 bt_sock_create+0x121/0x260 net/bluetooth/af_bluetooth.c:130 __sock_create+0x262/0x540 net/socket.c:1275 sock_create net/socket.c:1315 [inline] SYSC_socket net/socket.c:1345 [inline] SyS_socket+0xd5/0x1e0 net/socket.c:1325 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 9096: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 sk_prot_free net/core/sock.c:1504 [inline] __sk_destruct+0x47e/0x5a0 net/core/sock.c:1582 sk_destruct+0x83/0xb0 net/core/sock.c:1597 __sk_free+0x47/0x1f0 net/core/sock.c:1605 sk_free+0x1a/0x20 net/core/sock.c:1616 sock_put include/net/sock.h:1662 [inline] l2cap_sock_kill.part.2+0x52/0x60 net/bluetooth/l2cap_sock.c:1056 l2cap_sock_kill net/bluetooth/l2cap_sock.c:1216 [inline] l2cap_sock_release+0x1ce/0x230 net/bluetooth/l2cap_sock.c:1210 __sock_release+0xc2/0x2a0 net/socket.c:602 sock_close+0x10/0x20 net/socket.c:1139 __fput+0x232/0x740 fs/file_table.c:210 ____fput+0x9/0x10 fs/file_table.c:244 task_work_run+0xe5/0x170 kernel/task_work.c:113 get_signal+0x1447/0x1a90 kernel/signal.c:2234 do_signal+0x7f/0x18b0 arch/x86/kernel/signal.c:792 exit_to_usermode_loop+0x11e/0x190 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x416/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8881df70ae80 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 160 bytes inside of 2048-byte region [ffff8881df70ae80, ffff8881df70b680) The buggy address belongs to the page: page:ffffea00077dc280 count:1 mapcount:0 mapping:ffff8881df70a600 index:0x0 compound_mapcount: 0 flags: 0x17ffe0000008100(slab|head) raw: 017ffe0000008100 ffff8881df70a600 0000000000000000 0000000100000003 raw: ffffea00077de0a0 ffffea00077da3a0 ffff8881f6000c40 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881df70ae00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881df70ae80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881df70af00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881df70af80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881df70b000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================