[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 36.223327] random: sshd: uninitialized urandom read (32 bytes read) [ 36.468826] kauditd_printk_skb: 9 callbacks suppressed [ 36.468835] audit: type=1400 audit(1569032052.286:35): avc: denied { map } for pid=6790 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 [ 36.524392] random: sshd: uninitialized urandom read (32 bytes read) [ 37.054246] random: sshd: uninitialized urandom read (32 bytes read) [ 37.241130] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.120' (ECDSA) to the list of known hosts. [ 42.789667] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 42.900741] audit: type=1400 audit(1569032058.726:36): avc: denied { map } for pid=6802 comm="syz-executor930" path="/root/syz-executor930973954" dev="sda1" ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 42.928887] TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. [ 42.941507] ================================================================== [ 42.949035] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 42.955767] Read of size 2 at addr ffff8880962e9cb0 by task syz-executor930/6802 [ 42.963293] [ 42.964905] CPU: 1 PID: 6802 Comm: syz-executor930 Not tainted 4.14.145 #0 [ 42.971890] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.981227] Call Trace: [ 42.983801] dump_stack+0x138/0x197 [ 42.987408] ? tcp_init_tso_segs+0x1ae/0x200 [ 42.991793] print_address_description.cold+0x7c/0x1dc [ 42.997045] ? tcp_init_tso_segs+0x1ae/0x200 [ 43.001429] kasan_report.cold+0xa9/0x2af [ 43.005565] __asan_report_load2_noabort+0x14/0x20 [ 43.010475] tcp_init_tso_segs+0x1ae/0x200 [ 43.014683] ? tcp_tso_segs+0x7d/0x1c0 [ 43.018561] tcp_write_xmit+0x15e/0x4960 [ 43.022602] ? tcp_v6_md5_lookup+0x23/0x30 [ 43.026823] ? tcp_established_options+0x2c5/0x420 [ 43.031731] ? tcp_current_mss+0x1dc/0x2f0 [ 43.035944] ? __alloc_skb+0x3ee/0x500 [ 43.039815] __tcp_push_pending_frames+0xa6/0x260 [ 43.044646] tcp_send_fin+0x17e/0xc40 [ 43.048423] tcp_close+0xcc8/0xfb0 [ 43.051940] ? lock_acquire+0x16f/0x430 [ 43.055888] ? ip_mc_drop_socket+0x1d6/0x230 [ 43.060275] inet_release+0xec/0x1c0 [ 43.063967] inet6_release+0x53/0x80 [ 43.067658] __sock_release+0xce/0x2b0 [ 43.071525] ? __sock_release+0x2b0/0x2b0 [ 43.075687] sock_close+0x1b/0x30 [ 43.079146] __fput+0x275/0x7a0 [ 43.082433] ____fput+0x16/0x20 [ 43.085713] task_work_run+0x114/0x190 [ 43.089583] do_exit+0x7df/0x2c10 [ 43.093020] ? mm_update_next_owner+0x5d0/0x5d0 [ 43.097671] ? up_read+0x1a/0x40 [ 43.101028] ? __do_page_fault+0x358/0xb80 [ 43.105240] do_group_exit+0x111/0x330 [ 43.109107] SyS_exit_group+0x1d/0x20 [ 43.112885] ? do_group_exit+0x330/0x330 [ 43.116928] do_syscall_64+0x1e8/0x640 [ 43.120797] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 43.125619] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 43.130788] RIP: 0033:0x43ee88 [ 43.133956] RSP: 002b:00007ffcfe69d538 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 43.141816] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 43.149083] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 43.156334] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 43.163589] R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001 [ 43.170837] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 43.178101] [ 43.179705] Allocated by task 6802: [ 43.183317] save_stack_trace+0x16/0x20 [ 43.187275] save_stack+0x45/0xd0 [ 43.190710] kasan_kmalloc+0xce/0xf0 [ 43.194398] kasan_slab_alloc+0xf/0x20 [ 43.198262] kmem_cache_alloc_node+0x144/0x780 [ 43.202819] __alloc_skb+0x9c/0x500 [ 43.206443] sk_stream_alloc_skb+0xb3/0x780 [ 43.210740] tcp_sendmsg_locked+0xf61/0x3200 [ 43.215135] tcp_sendmsg+0x30/0x50 [ 43.218652] inet_sendmsg+0x122/0x500 [ 43.222427] sock_sendmsg+0xce/0x110 [ 43.226114] SYSC_sendto+0x206/0x310 [ 43.229803] SyS_sendto+0x40/0x50 [ 43.233238] do_syscall_64+0x1e8/0x640 [ 43.237104] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 43.242268] [ 43.243871] Freed by task 6802: [ 43.247128] save_stack_trace+0x16/0x20 [ 43.251108] save_stack+0x45/0xd0 [ 43.254545] kasan_slab_free+0x75/0xc0 [ 43.258425] kmem_cache_free+0x83/0x2b0 [ 43.262417] kfree_skbmem+0x8d/0x120 [ 43.266109] __kfree_skb+0x1e/0x30 [ 43.269629] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 43.274708] tcp_sendmsg_locked+0x1ced/0x3200 [ 43.279179] tcp_sendmsg+0x30/0x50 [ 43.282697] inet_sendmsg+0x122/0x500 [ 43.286485] sock_sendmsg+0xce/0x110 [ 43.290187] SYSC_sendto+0x206/0x310 [ 43.293875] SyS_sendto+0x40/0x50 [ 43.297306] do_syscall_64+0x1e8/0x640 [ 43.301189] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 43.306351] [ 43.307962] The buggy address belongs to the object at ffff8880962e9c80 [ 43.307962] which belongs to the cache skbuff_fclone_cache of size 472 [ 43.321289] The buggy address is located 48 bytes inside of [ 43.321289] 472-byte region [ffff8880962e9c80, ffff8880962e9e58) [ 43.333052] The buggy address belongs to the page: [ 43.337958] page:ffffea000258ba40 count:1 mapcount:0 mapping:ffff8880962e9000 index:0x0 [ 43.346087] flags: 0x1fffc0000000100(slab) [ 43.350300] raw: 01fffc0000000100 ffff8880962e9000 0000000000000000 0000000100000006 [ 43.358164] raw: ffffea00023ef860 ffff8880a9e1be48 ffff8880a9e19a80 0000000000000000 [ 43.366025] page dumped because: kasan: bad access detected [ 43.371707] [ 43.373308] Memory state around the buggy address: [ 43.378213] ffff8880962e9b80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc [ 43.385639] ffff8880962e9c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 43.392988] >ffff8880962e9c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 43.400343] ^ [ 43.405253] ffff8880962e9d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 43.412605] ffff8880962e9d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 43.419945] ================================================================== [ 43.427291] Disabling lock debugging due to kernel taint [ 43.434899] Kernel panic - not syncing: panic_on_warn set ... [ 43.434899] [ 43.442600] CPU: 0 PID: 6802 Comm: syz-executor930 Tainted: G B 4.14.145 #0 [ 43.450809] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.460146] Call Trace: [ 43.462718] dump_stack+0x138/0x197 [ 43.466423] ? tcp_init_tso_segs+0x1ae/0x200 [ 43.470881] panic+0x1f2/0x426 [ 43.474050] ? add_taint.cold+0x16/0x16 [ 43.478132] ? ___preempt_schedule+0x16/0x18 [ 43.482526] kasan_end_report+0x47/0x4f [ 43.486477] kasan_report.cold+0x130/0x2af [ 43.490688] __asan_report_load2_noabort+0x14/0x20 [ 43.495592] tcp_init_tso_segs+0x1ae/0x200 [ 43.499952] ? tcp_tso_segs+0x7d/0x1c0 [ 43.503821] tcp_write_xmit+0x15e/0x4960 [ 43.507872] ? tcp_v6_md5_lookup+0x23/0x30 [ 43.512093] ? tcp_established_options+0x2c5/0x420 [ 43.517044] ? tcp_current_mss+0x1dc/0x2f0 [ 43.521260] ? __alloc_skb+0x3ee/0x500 [ 43.525125] __tcp_push_pending_frames+0xa6/0x260 [ 43.529944] tcp_send_fin+0x17e/0xc40 [ 43.533719] tcp_close+0xcc8/0xfb0 [ 43.537237] ? lock_acquire+0x16f/0x430 [ 43.541189] ? ip_mc_drop_socket+0x1d6/0x230 [ 43.545571] inet_release+0xec/0x1c0 [ 43.549273] inet6_release+0x53/0x80 [ 43.552961] __sock_release+0xce/0x2b0 [ 43.556820] ? __sock_release+0x2b0/0x2b0 [ 43.560939] sock_close+0x1b/0x30 [ 43.564369] __fput+0x275/0x7a0 [ 43.567631] ____fput+0x16/0x20 [ 43.570896] task_work_run+0x114/0x190 [ 43.574761] do_exit+0x7df/0x2c10 [ 43.578212] ? mm_update_next_owner+0x5d0/0x5d0 [ 43.582857] ? up_read+0x1a/0x40 [ 43.586202] ? __do_page_fault+0x358/0xb80 [ 43.590411] do_group_exit+0x111/0x330 [ 43.594274] SyS_exit_group+0x1d/0x20 [ 43.598048] ? do_group_exit+0x330/0x330 [ 43.602094] do_syscall_64+0x1e8/0x640 [ 43.605955] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 43.610896] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 43.616077] RIP: 0033:0x43ee88 [ 43.619247] RSP: 002b:00007ffcfe69d538 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 43.626949] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 43.634282] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 43.641528] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 43.648776] R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001 [ 43.656019] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 43.664636] Kernel Offset: disabled [ 43.668298] Rebooting in 86400 seconds..