[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.048223] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.945914] random: sshd: uninitialized urandom read (32 bytes read) [ 24.418989] random: sshd: uninitialized urandom read (32 bytes read) [ 25.251902] random: sshd: uninitialized urandom read (32 bytes read) [ 25.415154] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.62' (ECDSA) to the list of known hosts. [ 30.878176] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 30.975219] ================================================================== [ 30.982748] BUG: KASAN: slab-out-of-bounds in bpf_skb_change_head+0x80c/0x9d0 [ 30.990021] Read of size 4 at addr ffff8801d94ea680 by task syz-executor991/4551 [ 30.997548] [ 30.999168] CPU: 0 PID: 4551 Comm: syz-executor991 Not tainted 4.17.0-rc7+ #38 [ 31.006509] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.015851] Call Trace: [ 31.018434] dump_stack+0x1b9/0x294 [ 31.022049] ? dump_stack_print_info.cold.2+0x52/0x52 [ 31.027225] ? printk+0x9e/0xba [ 31.030494] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 31.035235] ? kasan_check_write+0x14/0x20 [ 31.039455] print_address_description+0x6c/0x20b [ 31.044293] ? bpf_skb_change_head+0x80c/0x9d0 [ 31.048856] kasan_report.cold.7+0x242/0x2fe [ 31.053250] __asan_report_load4_noabort+0x14/0x20 [ 31.058161] bpf_skb_change_head+0x80c/0x9d0 [ 31.062567] ? depot_save_stack+0x26b/0x450 [ 31.066889] ? bpf_skb_vlan_push+0x720/0x720 [ 31.071295] ? find_held_lock+0x36/0x1c0 [ 31.075351] ? lock_downgrade+0x8e0/0x8e0 [ 31.079489] ? rcu_pm_notify+0xc0/0xc0 [ 31.083381] ? pvclock_read_flags+0x160/0x160 [ 31.087862] ? rcu_read_lock_sched_held+0x108/0x120 [ 31.092867] ? kmem_cache_alloc+0x5fa/0x760 [ 31.097173] ? ktime_get+0x33e/0x430 [ 31.100877] ? lock_acquire+0x1dc/0x520 [ 31.104839] ? bpf_test_run+0x1f3/0x3b0 [ 31.108802] ? kasan_check_read+0x11/0x20 [ 31.112932] ? rcu_is_watching+0x85/0x140 [ 31.117065] ? rcu_bh_force_quiescent_state+0x20/0x20 [ 31.122242] ? __might_sleep+0x95/0x190 [ 31.126200] ? bpf_test_run+0xaf/0x3b0 [ 31.130075] ? bpf_prog_test_run_skb+0x622/0xa20 [ 31.134826] ? bpf_test_finish.isra.7+0x1e0/0x1e0 [ 31.139654] ? bpf_prog_add+0x69/0xd0 [ 31.143463] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 31.148997] ? __bpf_prog_get+0x9b/0x290 [ 31.153059] ? bpf_test_finish.isra.7+0x1e0/0x1e0 [ 31.157891] ? bpf_prog_test_run+0x130/0x1a0 [ 31.162291] ? __x64_sys_bpf+0x3d8/0x510 [ 31.166334] ? bpf_prog_get+0x20/0x20 [ 31.170141] ? do_syscall_64+0x92/0x800 [ 31.174104] ? do_syscall_64+0x1b1/0x800 [ 31.178149] ? syscall_slow_exit_work+0x4f0/0x4f0 [ 31.183002] ? syscall_return_slowpath+0x5c0/0x5c0 [ 31.187947] ? syscall_return_slowpath+0x30f/0x5c0 [ 31.192872] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 31.198224] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.203054] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.208401] [ 31.210015] Allocated by task 0: [ 31.213364] (stack is not available) [ 31.217062] [ 31.218680] Freed by task 0: [ 31.221676] (stack is not available) [ 31.225365] [ 31.226984] The buggy address belongs to the object at ffff8801d94ea580 [ 31.226984] which belongs to the cache skbuff_head_cache of size 232 [ 31.240150] The buggy address is located 24 bytes to the right of [ 31.240150] 232-byte region [ffff8801d94ea580, ffff8801d94ea668) [ 31.252445] The buggy address belongs to the page: [ 31.257362] page:ffffea0007653a80 count:1 mapcount:0 mapping:ffff8801d94ea080 index:0x0 [ 31.265489] flags: 0x2fffc0000000100(slab) [ 31.269711] raw: 02fffc0000000100 ffff8801d94ea080 0000000000000000 000000010000000c [ 31.277581] raw: ffffea0006b2e720 ffffea00076595e0 ffff8801d9450e40 0000000000000000 [ 31.285453] page dumped because: kasan: bad access detected [ 31.291157] [ 31.292777] Memory state around the buggy address: [ 31.297689] ffff8801d94ea580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.305044] ffff8801d94ea600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.312396] >ffff8801d94ea680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.319741] ^ [ 31.323091] ffff8801d94ea700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.330434] ffff8801d94ea780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.337772] ================================================================== [ 31.345118] Disabling lock debugging due to kernel taint [ 31.350672] Kernel panic - not syncing: panic_on_warn set ... [ 31.350672] [ 31.358054] CPU: 0 PID: 4551 Comm: syz-executor991 Tainted: G B 4.17.0-rc7+ #38 [ 31.366793] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.376151] Call Trace: [ 31.378735] dump_stack+0x1b9/0x294 [ 31.382346] ? dump_stack_print_info.cold.2+0x52/0x52 [ 31.387533] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 31.392282] ? bpf_skb_change_head+0x710/0x9d0 [ 31.396847] panic+0x22f/0x4de [ 31.400027] ? add_taint.cold.5+0x16/0x16 [ 31.404165] ? do_raw_spin_unlock+0x9e/0x2e0 [ 31.408559] ? do_raw_spin_unlock+0x9e/0x2e0 [ 31.412957] ? bpf_skb_change_head+0x80c/0x9d0 [ 31.417540] kasan_end_report+0x47/0x4f [ 31.421502] kasan_report.cold.7+0x76/0x2fe [ 31.425811] __asan_report_load4_noabort+0x14/0x20 [ 31.430728] bpf_skb_change_head+0x80c/0x9d0 [ 31.435122] ? depot_save_stack+0x26b/0x450 [ 31.439428] ? bpf_skb_vlan_push+0x720/0x720 [ 31.443821] ? find_held_lock+0x36/0x1c0 [ 31.447878] ? lock_downgrade+0x8e0/0x8e0 [ 31.452013] ? rcu_pm_notify+0xc0/0xc0 [ 31.455889] ? pvclock_read_flags+0x160/0x160 [ 31.460367] ? rcu_read_lock_sched_held+0x108/0x120 [ 31.465366] ? kmem_cache_alloc+0x5fa/0x760 [ 31.469675] ? ktime_get+0x33e/0x430 [ 31.473382] ? lock_acquire+0x1dc/0x520 [ 31.477339] ? bpf_test_run+0x1f3/0x3b0 [ 31.481295] ? kasan_check_read+0x11/0x20 [ 31.485425] ? rcu_is_watching+0x85/0x140 [ 31.489563] ? rcu_bh_force_quiescent_state+0x20/0x20 [ 31.494745] ? __might_sleep+0x95/0x190 [ 31.498705] ? bpf_test_run+0xaf/0x3b0 [ 31.502578] ? bpf_prog_test_run_skb+0x622/0xa20 [ 31.507343] ? bpf_test_finish.isra.7+0x1e0/0x1e0 [ 31.512184] ? bpf_prog_add+0x69/0xd0 [ 31.515982] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 31.521504] ? __bpf_prog_get+0x9b/0x290 [ 31.525550] ? bpf_test_finish.isra.7+0x1e0/0x1e0 [ 31.530385] ? bpf_prog_test_run+0x130/0x1a0 [ 31.534776] ? __x64_sys_bpf+0x3d8/0x510 [ 31.538820] ? bpf_prog_get+0x20/0x20 [ 31.542607] ? do_syscall_64+0x92/0x800 [ 31.546567] ? do_syscall_64+0x1b1/0x800 [ 31.550610] ? syscall_slow_exit_work+0x4f0/0x4f0 [ 31.555439] ? syscall_return_slowpath+0x5c0/0x5c0 [ 31.560353] ? syscall_return_slowpath+0x30f/0x5c0 [ 31.565271] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 31.570630] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.575462] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.581314] Dumping ftrace buffer: [ 31.584861] (ftrace buffer empty) [ 31.588553] Kernel Offset: disabled [ 31.592163] Rebooting in 86400 seconds..