[....] Starting OpenBSD Secure Shell server: sshd[ 31.619778] audit: type=1800 audit(1569003182.308:34): pid=6792 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="startpar" name="rmnologin" dev="sda1" ino=2456 res=0 [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 39.291185] random: sshd: uninitialized urandom read (32 bytes read) [ 39.833892] audit: type=1400 audit(1569003190.558:35): avc: denied { map } for pid=6963 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 [ 39.887036] random: sshd: uninitialized urandom read (32 bytes read) [ 40.437208] random: sshd: uninitialized urandom read (32 bytes read) [ 40.632055] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.93' (ECDSA) to the list of known hosts. [ 46.204249] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 46.323411] audit: type=1400 audit(1569003197.048:36): avc: denied { map } for pid=6976 comm="syz-executor169" path="/root/syz-executor169106891" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 46.352818] ================================================================== [ 46.360531] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 46.367442] Read of size 2 at addr ffff8880a6361d30 by task syz-executor169/6976 [ 46.374955] [ 46.376563] CPU: 0 PID: 6976 Comm: syz-executor169 Not tainted 4.14.145 #0 [ 46.383576] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.393082] Call Trace: [ 46.395665] dump_stack+0x138/0x197 [ 46.399269] ? rdma_ah_conv_opa_to_ib+0x188/0x4c0 [ 46.404105] ? tcp_init_tso_segs+0x1ae/0x200 [ 46.408492] print_address_description.cold+0x7c/0x1dc [ 46.413747] ? tcp_init_tso_segs+0x1ae/0x200 [ 46.418133] kasan_report.cold+0xa9/0x2af [ 46.422262] __asan_report_load2_noabort+0x14/0x20 [ 46.427172] tcp_init_tso_segs+0x1ae/0x200 [ 46.431385] ? tcp_tso_segs+0x7d/0x1c0 [ 46.435256] tcp_write_xmit+0x15e/0x4960 [ 46.439298] ? tcp_v6_md5_lookup+0x23/0x30 [ 46.443515] ? tcp_established_options+0x2c5/0x420 [ 46.448429] ? tcp_current_mss+0x1dc/0x2f0 [ 46.452667] ? __alloc_skb+0x3ee/0x500 [ 46.456546] __tcp_push_pending_frames+0xa6/0x260 [ 46.461367] tcp_send_fin+0x17e/0xc40 [ 46.465144] tcp_close+0xcc8/0xfb0 [ 46.468671] ? lock_acquire+0x16f/0x430 [ 46.472628] ? ip_mc_drop_socket+0x1d6/0x230 [ 46.477104] inet_release+0xec/0x1c0 [ 46.480810] inet6_release+0x53/0x80 [ 46.484507] __sock_release+0xce/0x2b0 [ 46.488383] ? __sock_release+0x2b0/0x2b0 [ 46.492510] sock_close+0x1b/0x30 [ 46.495949] __fput+0x275/0x7a0 [ 46.499211] ____fput+0x16/0x20 [ 46.502470] task_work_run+0x114/0x190 [ 46.506352] do_exit+0x7df/0x2c10 [ 46.509785] ? mm_update_next_owner+0x5d0/0x5d0 [ 46.514521] ? fd_install+0x4d/0x60 [ 46.518128] ? sock_map_fd+0x56/0x80 [ 46.521822] ? SyS_socket+0x103/0x170 [ 46.525610] do_group_exit+0x111/0x330 [ 46.529569] SyS_exit_group+0x1d/0x20 [ 46.533348] ? do_group_exit+0x330/0x330 [ 46.537394] do_syscall_64+0x1e8/0x640 [ 46.541260] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 46.546235] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 46.551420] RIP: 0033:0x43ee88 [ 46.554593] RSP: 002b:00007ffdea1090f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 46.562283] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 46.569535] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 46.576948] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 46.584207] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 46.591614] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 46.598910] [ 46.600523] Allocated by task 6976: [ 46.604140] save_stack_trace+0x16/0x20 [ 46.608096] save_stack+0x45/0xd0 [ 46.611537] kasan_kmalloc+0xce/0xf0 [ 46.615227] kasan_slab_alloc+0xf/0x20 [ 46.619091] kmem_cache_alloc_node+0x144/0x780 [ 46.623652] __alloc_skb+0x9c/0x500 [ 46.627297] sk_stream_alloc_skb+0xb3/0x780 [ 46.631609] tcp_sendmsg_locked+0xf61/0x3200 [ 46.636003] tcp_sendmsg+0x30/0x50 [ 46.639530] inet_sendmsg+0x122/0x500 [ 46.643316] sock_sendmsg+0xce/0x110 [ 46.647008] SYSC_sendto+0x206/0x310 [ 46.650697] SyS_sendto+0x40/0x50 [ 46.654416] do_syscall_64+0x1e8/0x640 [ 46.658286] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 46.663451] [ 46.665077] Freed by task 6976: [ 46.668355] save_stack_trace+0x16/0x20 [ 46.672381] save_stack+0x45/0xd0 [ 46.675819] kasan_slab_free+0x75/0xc0 [ 46.679687] kmem_cache_free+0x83/0x2b0 [ 46.683645] kfree_skbmem+0x8d/0x120 [ 46.687336] __kfree_skb+0x1e/0x30 [ 46.690855] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 46.696180] tcp_sendmsg_locked+0x1ced/0x3200 [ 46.700698] tcp_sendmsg+0x30/0x50 [ 46.704242] inet_sendmsg+0x122/0x500 [ 46.708024] sock_sendmsg+0xce/0x110 [ 46.711735] SYSC_sendto+0x206/0x310 [ 46.715456] SyS_sendto+0x40/0x50 [ 46.718922] do_syscall_64+0x1e8/0x640 [ 46.722798] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 46.727972] [ 46.729589] The buggy address belongs to the object at ffff8880a6361d00 [ 46.729589] which belongs to the cache skbuff_fclone_cache of size 472 [ 46.742933] The buggy address is located 48 bytes inside of [ 46.742933] 472-byte region [ffff8880a6361d00, ffff8880a6361ed8) [ 46.754702] The buggy address belongs to the page: [ 46.759629] page:ffffea000298d840 count:1 mapcount:0 mapping:ffff8880a6361080 index:0x0 [ 46.767850] flags: 0x1fffc0000000100(slab) [ 46.772160] raw: 01fffc0000000100 ffff8880a6361080 0000000000000000 0000000100000006 [ 46.780022] raw: ffffea000253d520 ffff8880a9e81e48 ffff8880a9e83d80 0000000000000000 [ 46.787891] page dumped because: kasan: bad access detected [ 46.793584] [ 46.795199] Memory state around the buggy address: [ 46.800124] ffff8880a6361c00: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc [ 46.807568] ffff8880a6361c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 46.814905] >ffff8880a6361d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 46.822250] ^ [ 46.827154] ffff8880a6361d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 46.834495] ffff8880a6361e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 46.841834] ================================================================== [ 46.849442] Disabling lock debugging due to kernel taint [ 46.855737] Kernel panic - not syncing: panic_on_warn set ... [ 46.855737] [ 46.863122] CPU: 1 PID: 6976 Comm: syz-executor169 Tainted: G B 4.14.145 #0 [ 46.871339] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.880672] Call Trace: [ 46.883357] dump_stack+0x138/0x197 [ 46.886994] ? tcp_init_tso_segs+0x1ae/0x200 [ 46.891391] panic+0x1f2/0x426 [ 46.894563] ? add_taint.cold+0x16/0x16 [ 46.898528] ? ___preempt_schedule+0x16/0x18 [ 46.902920] kasan_end_report+0x47/0x4f [ 46.906996] kasan_report.cold+0x130/0x2af [ 46.911216] __asan_report_load2_noabort+0x14/0x20 [ 46.916125] tcp_init_tso_segs+0x1ae/0x200 [ 46.920347] ? tcp_tso_segs+0x7d/0x1c0 [ 46.924226] tcp_write_xmit+0x15e/0x4960 [ 46.928277] ? tcp_v6_md5_lookup+0x23/0x30 [ 46.932507] ? tcp_established_options+0x2c5/0x420 [ 46.937512] ? tcp_current_mss+0x1dc/0x2f0 [ 46.941739] ? __alloc_skb+0x3ee/0x500 [ 46.945611] __tcp_push_pending_frames+0xa6/0x260 [ 46.950433] tcp_send_fin+0x17e/0xc40 [ 46.954214] tcp_close+0xcc8/0xfb0 [ 46.957745] ? lock_acquire+0x16f/0x430 [ 46.961699] ? ip_mc_drop_socket+0x1d6/0x230 [ 46.966172] inet_release+0xec/0x1c0 [ 46.969876] inet6_release+0x53/0x80 [ 46.973580] __sock_release+0xce/0x2b0 [ 46.977449] ? __sock_release+0x2b0/0x2b0 [ 46.981575] sock_close+0x1b/0x30 [ 46.985010] __fput+0x275/0x7a0 [ 46.988274] ____fput+0x16/0x20 [ 46.991551] task_work_run+0x114/0x190 [ 46.995436] do_exit+0x7df/0x2c10 [ 46.998889] ? mm_update_next_owner+0x5d0/0x5d0 [ 47.003538] ? fd_install+0x4d/0x60 [ 47.007146] ? sock_map_fd+0x56/0x80 [ 47.010864] ? SyS_socket+0x103/0x170 [ 47.014652] do_group_exit+0x111/0x330 [ 47.018520] SyS_exit_group+0x1d/0x20 [ 47.022338] ? do_group_exit+0x330/0x330 [ 47.026557] do_syscall_64+0x1e8/0x640 [ 47.030431] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 47.035262] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.040438] RIP: 0033:0x43ee88 [ 47.043618] RSP: 002b:00007ffdea1090f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 47.051320] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 47.058781] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 47.066039] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 47.073294] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 47.080732] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 47.089560] Kernel Offset: disabled [ 47.093195] Rebooting in 86400 seconds..