INIT: Entering runlevel: 2 [info] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.10.5' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 30.435536] ================================================================== [ 30.442955] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 30.450230] Read of size 4 at addr ffff8801b79a0780 by task syzkaller646172/3775 [ 30.457730] [ 30.459330] CPU: 0 PID: 3775 Comm: syzkaller646172 Not tainted 4.9.92-g7cd9561 #1 [ 30.466919] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.476245] ffff8801c37b7cb0 ffffffff81d9c489 ffffea0006de6800 ffff8801b79a0780 [ 30.484214] 0000000000000000 ffff8801b79a0780 ffffffff82ef0be0 ffff8801c37b7ce8 [ 30.492195] ffffffff8156556b ffff8801b79a0780 0000000000000004 0000000000000000 [ 30.500186] Call Trace: [ 30.502759] [] dump_stack+0xc1/0x128 [ 30.508104] [] ? sock_release+0x1c0/0x1c0 [ 30.513896] [] print_address_description+0x6c/0x234 [ 30.520538] [] ? sock_release+0x1c0/0x1c0 [ 30.526576] [] kasan_report.cold.6+0xac/0x2f5 [ 30.532697] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 30.539431] [] __asan_report_load4_noabort+0x14/0x20 [ 30.546154] [] l2tp_session_queue_purge+0xf4/0x100 [ 30.552705] [] ? sock_release+0x1c0/0x1c0 [ 30.558481] [] pppol2tp_release+0x1fb/0x2e0 [ 30.564434] [] sock_release+0x96/0x1c0 [ 30.569950] [] sock_close+0x16/0x20 [ 30.575202] [] __fput+0x263/0x700 [ 30.580277] [] ____fput+0x15/0x20 [ 30.585367] [] task_work_run+0x10c/0x180 [ 30.591048] [] exit_to_usermode_loop+0xfc/0x120 [ 30.597339] [] do_syscall_64+0x364/0x490 [ 30.603027] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.609932] [ 30.611533] Allocated by task 3774: [ 30.615132] save_stack_trace+0x16/0x20 [ 30.619077] save_stack+0x43/0xd0 [ 30.622500] kasan_kmalloc+0xc7/0xe0 [ 30.626185] __kmalloc+0x11d/0x300 [ 30.629695] l2tp_session_create+0x38/0x1760 [ 30.634073] pppol2tp_connect+0x10c5/0x18e0 [ 30.638367] SYSC_connect+0x1b8/0x300 [ 30.642150] SyS_connect+0x24/0x30 [ 30.645658] do_syscall_64+0x1a6/0x490 [ 30.649521] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.654603] [ 30.656203] Freed by task 3774: [ 30.659458] save_stack_trace+0x16/0x20 [ 30.663405] save_stack+0x43/0xd0 [ 30.666831] kasan_slab_free+0x72/0xc0 [ 30.670689] kfree+0xfb/0x310 [ 30.673766] l2tp_session_free+0x166/0x200 [ 30.677981] l2tp_tunnel_closeall+0x284/0x350 [ 30.682466] l2tp_udp_encap_destroy+0x87/0xe0 [ 30.686932] udpv6_destroy_sock+0xb1/0xd0 [ 30.691059] sk_common_release+0x6d/0x300 [ 30.695176] udp_lib_close+0x15/0x20 [ 30.698863] inet_release+0xff/0x1d0 [ 30.702548] inet6_release+0x50/0x70 [ 30.706232] sock_release+0x96/0x1c0 [ 30.709921] sock_close+0x16/0x20 [ 30.713344] __fput+0x263/0x700 [ 30.716595] ____fput+0x15/0x20 [ 30.719850] task_work_run+0x10c/0x180 [ 30.723711] exit_to_usermode_loop+0xfc/0x120 [ 30.728178] do_syscall_64+0x364/0x490 [ 30.732056] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.737134] [ 30.738735] The buggy address belongs to the object at ffff8801b79a0780 [ 30.738735] which belongs to the cache kmalloc-512 of size 512 [ 30.751375] The buggy address is located 0 bytes inside of [ 30.751375] 512-byte region [ffff8801b79a0780, ffff8801b79a0980) [ 30.763221] The buggy address belongs to the page: [ 30.768125] page:ffffea0006de6800 count:1 mapcount:0 mapping: (null) index:0xffff8801b79a1b80 compound_mapcount: 0 [ 30.779598] flags: 0x8000000000004080(slab|head) [ 30.784321] page dumped because: kasan: bad access detected [ 30.789999] [ 30.791595] Memory state around the buggy address: [ 30.796511] ffff8801b79a0680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.803842] ffff8801b79a0700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 30.811175] >ffff8801b79a0780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.818505] ^ [ 30.821855] ffff8801b79a0800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.829186] ffff8801b79a0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 30.836513] ================================================================== [ 30.843841] Disabling lock debugging due to kernel taint [ 30.849417] Kernel panic - not syncing: panic_on_warn set ... [ 30.849417] [ 30.856758] CPU: 0 PID: 3775 Comm: syzkaller646172 Tainted: G B 4.9.92-g7cd9561 #1 [ 30.865565] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.874907] ffff8801c37b7c10 ffffffff81d9c489 ffffffff841a85f1 00000000ffffffff [ 30.882979] 0000000000000000 0000000000000000 ffffffff82ef0be0 ffff8801c37b7cd0 [ 30.890966] ffffffff8141fa55 0000000041b58ab3 ffffffff8419bd28 ffffffff8141f896 [ 30.898950] Call Trace: [ 30.901512] [] dump_stack+0xc1/0x128 [ 30.906845] [] ? sock_release+0x1c0/0x1c0 [ 30.912620] [] panic+0x1bf/0x3bc [ 30.917607] [] ? add_taint.cold.6+0x16/0x16 [ 30.923551] [] ? ___preempt_schedule+0x16/0x18 [ 30.929753] [] kasan_end_report+0x47/0x4f [ 30.935519] [] kasan_report.cold.6+0xc9/0x2f5 [ 30.941638] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 30.948363] [] __asan_report_load4_noabort+0x14/0x20 [ 30.955085] [] l2tp_session_queue_purge+0xf4/0x100 [ 30.961638] [] ? sock_release+0x1c0/0x1c0 [ 30.967406] [] pppol2tp_release+0x1fb/0x2e0 [ 30.974303] [] sock_release+0x96/0x1c0 [ 30.979811] [] sock_close+0x16/0x20 [ 30.985056] [] __fput+0x263/0x700 [ 30.990130] [] ____fput+0x15/0x20 [ 30.995209] [] task_work_run+0x10c/0x180 [ 31.000892] [] exit_to_usermode_loop+0xfc/0x120 [ 31.007181] [] do_syscall_64+0x364/0x490 [ 31.012867] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.020196] Dumping ftrace buffer: [ 31.023713] (ftrace buffer empty) [ 31.027393] Kernel Offset: disabled [ 31.030997] Rebooting in 86400 seconds..