[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.835273] random: sshd: uninitialized urandom read (32 bytes read) [ 32.172310] kauditd_printk_skb: 10 callbacks suppressed [ 32.172318] audit: type=1400 audit(1569012162.695:35): avc: denied { map } for pid=6911 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 [ 32.228157] random: sshd: uninitialized urandom read (32 bytes read) [ 32.803535] random: sshd: uninitialized urandom read (32 bytes read) [ 32.997533] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.172' (ECDSA) to the list of known hosts. [ 38.565769] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 38.685825] audit: type=1400 audit(1569012169.205:36): avc: denied { map } for pid=6924 comm="syz-executor836" path="/root/syz-executor836495377" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 38.716116] ================================================================== [ 38.723659] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 38.730400] Read of size 2 at addr ffff88808a3202b0 by task syz-executor836/6924 [ 38.737915] [ 38.739572] CPU: 0 PID: 6924 Comm: syz-executor836 Not tainted 4.14.145 #0 [ 38.746583] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.756109] Call Trace: [ 38.758697] dump_stack+0x138/0x197 [ 38.762324] ? tcp_init_tso_segs+0x1ae/0x200 [ 38.766729] print_address_description.cold+0x7c/0x1dc [ 38.772004] ? tcp_init_tso_segs+0x1ae/0x200 [ 38.776420] kasan_report.cold+0xa9/0x2af [ 38.780741] __asan_report_load2_noabort+0x14/0x20 [ 38.785673] tcp_init_tso_segs+0x1ae/0x200 [ 38.790189] ? tcp_tso_segs+0x7d/0x1c0 [ 38.794069] tcp_write_xmit+0x15e/0x4960 [ 38.798386] ? tcp_v6_md5_lookup+0x23/0x30 [ 38.802624] ? tcp_established_options+0x2c5/0x420 [ 38.807538] ? tcp_current_mss+0x1dc/0x2f0 [ 38.811776] ? __alloc_skb+0x3ee/0x500 [ 38.815727] __tcp_push_pending_frames+0xa6/0x260 [ 38.820584] tcp_send_fin+0x17e/0xc40 [ 38.824540] tcp_close+0xcc8/0xfb0 [ 38.828220] ? lock_acquire+0x16f/0x430 [ 38.832270] ? ip_mc_drop_socket+0x1d6/0x230 [ 38.836871] inet_release+0xec/0x1c0 [ 38.840593] inet6_release+0x53/0x80 [ 38.844300] __sock_release+0xce/0x2b0 [ 38.848239] ? __sock_release+0x2b0/0x2b0 [ 38.852370] sock_close+0x1b/0x30 [ 38.855814] __fput+0x275/0x7a0 [ 38.859080] ____fput+0x16/0x20 [ 38.862454] task_work_run+0x114/0x190 [ 38.866426] do_exit+0x7df/0x2c10 [ 38.869880] ? mm_update_next_owner+0x5d0/0x5d0 [ 38.874537] ? fd_install+0x4d/0x60 [ 38.878171] ? sock_map_fd+0x56/0x80 [ 38.882014] ? SyS_socket+0x103/0x170 [ 38.885831] do_group_exit+0x111/0x330 [ 38.889713] SyS_exit_group+0x1d/0x20 [ 38.893498] ? do_group_exit+0x330/0x330 [ 38.897550] do_syscall_64+0x1e8/0x640 [ 38.901420] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 38.906351] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.911526] RIP: 0033:0x43ee88 [ 38.914737] RSP: 002b:00007ffffa054eb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 38.922430] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 38.929896] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 38.937594] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 38.945007] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 38.952326] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 38.959600] [ 38.961223] Allocated by task 6924: [ 38.964938] save_stack_trace+0x16/0x20 [ 38.969422] save_stack+0x45/0xd0 [ 38.973071] kasan_kmalloc+0xce/0xf0 [ 38.976780] kasan_slab_alloc+0xf/0x20 [ 38.980757] kmem_cache_alloc_node+0x144/0x780 [ 38.986194] __alloc_skb+0x9c/0x500 [ 38.989848] sk_stream_alloc_skb+0xb3/0x780 [ 38.994159] tcp_sendmsg_locked+0xf61/0x3200 [ 38.998650] tcp_sendmsg+0x30/0x50 [ 39.002353] inet_sendmsg+0x122/0x500 [ 39.006245] sock_sendmsg+0xce/0x110 [ 39.010140] SYSC_sendto+0x206/0x310 [ 39.013854] SyS_sendto+0x40/0x50 [ 39.017396] do_syscall_64+0x1e8/0x640 [ 39.021358] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.027031] [ 39.029625] Freed by task 6924: [ 39.033226] save_stack_trace+0x16/0x20 [ 39.037703] save_stack+0x45/0xd0 [ 39.044369] kasan_slab_free+0x75/0xc0 [ 39.048652] kmem_cache_free+0x83/0x2b0 [ 39.052811] kfree_skbmem+0x8d/0x120 [ 39.057958] __kfree_skb+0x1e/0x30 [ 39.061843] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 39.066943] tcp_sendmsg_locked+0x1ced/0x3200 [ 39.071417] tcp_sendmsg+0x30/0x50 [ 39.074938] inet_sendmsg+0x122/0x500 [ 39.078724] sock_sendmsg+0xce/0x110 [ 39.082422] SYSC_sendto+0x206/0x310 [ 39.086124] SyS_sendto+0x40/0x50 [ 39.089570] do_syscall_64+0x1e8/0x640 [ 39.093462] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.098635] [ 39.100244] The buggy address belongs to the object at ffff88808a320280 [ 39.100244] which belongs to the cache skbuff_fclone_cache of size 472 [ 39.113706] The buggy address is located 48 bytes inside of [ 39.113706] 472-byte region [ffff88808a320280, ffff88808a320458) [ 39.125536] The buggy address belongs to the page: [ 39.130455] page:ffffea000228c800 count:1 mapcount:0 mapping:ffff88808a320000 index:0x0 [ 39.138593] flags: 0x1fffc0000000100(slab) [ 39.142815] raw: 01fffc0000000100 ffff88808a320000 0000000000000000 0000000100000006 [ 39.150682] raw: ffffea00024c4be0 ffffea0002a03c60 ffff88821b75f3c0 0000000000000000 [ 39.158904] page dumped because: kasan: bad access detected [ 39.164600] [ 39.166207] Memory state around the buggy address: [ 39.171119] ffff88808a320180: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc [ 39.178561] ffff88808a320200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 39.185906] >ffff88808a320280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.193253] ^ [ 39.198600] ffff88808a320300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.206037] ffff88808a320380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.213379] ================================================================== [ 39.220732] Disabling lock debugging due to kernel taint [ 39.228462] Kernel panic - not syncing: panic_on_warn set ... [ 39.228462] [ 39.236055] CPU: 1 PID: 6924 Comm: syz-executor836 Tainted: G B 4.14.145 #0 [ 39.244266] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.253622] Call Trace: [ 39.256200] dump_stack+0x138/0x197 [ 39.259827] ? tcp_init_tso_segs+0x1ae/0x200 [ 39.264217] panic+0x1f2/0x426 [ 39.267411] ? add_taint.cold+0x16/0x16 [ 39.271367] ? ___preempt_schedule+0x16/0x18 [ 39.275763] kasan_end_report+0x47/0x4f [ 39.279720] kasan_report.cold+0x130/0x2af [ 39.283939] __asan_report_load2_noabort+0x14/0x20 [ 39.288865] tcp_init_tso_segs+0x1ae/0x200 [ 39.293080] ? tcp_tso_segs+0x7d/0x1c0 [ 39.296953] tcp_write_xmit+0x15e/0x4960 [ 39.301014] ? tcp_v6_md5_lookup+0x23/0x30 [ 39.305233] ? tcp_established_options+0x2c5/0x420 [ 39.310143] ? tcp_current_mss+0x1dc/0x2f0 [ 39.314359] ? __alloc_skb+0x3ee/0x500 [ 39.318229] __tcp_push_pending_frames+0xa6/0x260 [ 39.323055] tcp_send_fin+0x17e/0xc40 [ 39.326835] tcp_close+0xcc8/0xfb0 [ 39.330371] ? lock_acquire+0x16f/0x430 [ 39.334330] ? ip_mc_drop_socket+0x1d6/0x230 [ 39.338722] inet_release+0xec/0x1c0 [ 39.342419] inet6_release+0x53/0x80 [ 39.346115] __sock_release+0xce/0x2b0 [ 39.349985] ? __sock_release+0x2b0/0x2b0 [ 39.354114] sock_close+0x1b/0x30 [ 39.357617] __fput+0x275/0x7a0 [ 39.360885] ____fput+0x16/0x20 [ 39.364151] task_work_run+0x114/0x190 [ 39.368019] do_exit+0x7df/0x2c10 [ 39.371454] ? mm_update_next_owner+0x5d0/0x5d0 [ 39.376123] ? fd_install+0x4d/0x60 [ 39.379740] ? sock_map_fd+0x56/0x80 [ 39.383438] ? SyS_socket+0x103/0x170 [ 39.387220] do_group_exit+0x111/0x330 [ 39.391234] SyS_exit_group+0x1d/0x20 [ 39.395017] ? do_group_exit+0x330/0x330 [ 39.399078] do_syscall_64+0x1e8/0x640 [ 39.402953] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 39.407798] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.412968] RIP: 0033:0x43ee88 [ 39.416137] RSP: 002b:00007ffffa054eb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 39.423839] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 39.431101] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 39.438350] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 39.445599] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 39.452849] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 39.461593] Kernel Offset: disabled [ 39.465220] Rebooting in 86400 seconds..