[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 32.954567] random: sshd: uninitialized urandom read (32 bytes read) [ 33.236762] kauditd_printk_skb: 9 callbacks suppressed [ 33.236769] audit: type=1400 audit(1569008336.309:35): avc: denied { map } for pid=6779 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 [ 33.290953] random: sshd: uninitialized urandom read (32 bytes read) [ 33.814513] random: sshd: uninitialized urandom read (32 bytes read) [ 33.991918] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.28' (ECDSA) to the list of known hosts. [ 39.534677] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 39.649042] audit: type=1400 audit(1569008342.719:36): avc: denied { map } for pid=6792 comm="syz-executor660" path="/root/syz-executor660517628" 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 [ 39.677456] ================================================================== [ 39.684983] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 39.691716] Read of size 2 at addr ffff8880995f82f0 by task syz-executor660/6792 [ 39.699224] [ 39.700884] CPU: 1 PID: 6792 Comm: syz-executor660 Not tainted 4.14.145 #0 [ 39.707872] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.717211] Call Trace: [ 39.719796] dump_stack+0x138/0x197 [ 39.723406] ? tcp_init_tso_segs+0x1ae/0x200 [ 39.727794] print_address_description.cold+0x7c/0x1dc [ 39.733050] ? tcp_init_tso_segs+0x1ae/0x200 [ 39.737442] kasan_report.cold+0xa9/0x2af [ 39.741574] __asan_report_load2_noabort+0x14/0x20 [ 39.746483] tcp_init_tso_segs+0x1ae/0x200 [ 39.750696] ? tcp_tso_segs+0x7d/0x1c0 [ 39.754914] tcp_write_xmit+0x15e/0x4960 [ 39.758957] ? tcp_v6_md5_lookup+0x23/0x30 [ 39.763171] ? tcp_established_options+0x2c5/0x420 [ 39.768085] ? tcp_current_mss+0x1dc/0x2f0 [ 39.772301] ? __alloc_skb+0x3ee/0x500 [ 39.776190] __tcp_push_pending_frames+0xa6/0x260 [ 39.781016] tcp_send_fin+0x17e/0xc40 [ 39.784798] tcp_close+0xcc8/0xfb0 [ 39.788319] ? lock_acquire+0x16f/0x430 [ 39.792274] ? ip_mc_drop_socket+0x1d6/0x230 [ 39.796661] inet_release+0xec/0x1c0 [ 39.800354] inet6_release+0x53/0x80 [ 39.804047] __sock_release+0xce/0x2b0 [ 39.807942] ? __sock_release+0x2b0/0x2b0 [ 39.812081] sock_close+0x1b/0x30 [ 39.815516] __fput+0x275/0x7a0 [ 39.818777] ____fput+0x16/0x20 [ 39.822035] task_work_run+0x114/0x190 [ 39.825920] do_exit+0x7df/0x2c10 [ 39.829356] ? mm_update_next_owner+0x5d0/0x5d0 [ 39.834021] ? fd_install+0x4d/0x60 [ 39.837627] ? sock_map_fd+0x56/0x80 [ 39.841755] ? SyS_socket+0x103/0x170 [ 39.845552] do_group_exit+0x111/0x330 [ 39.849437] SyS_exit_group+0x1d/0x20 [ 39.853216] ? do_group_exit+0x330/0x330 [ 39.857257] do_syscall_64+0x1e8/0x640 [ 39.861123] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 39.865976] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.871144] RIP: 0033:0x43ee88 [ 39.874329] RSP: 002b:00007ffc7cef9bf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 39.882016] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 39.889283] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 39.896553] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 39.903811] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 39.911064] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 39.918319] [ 39.919926] Allocated by task 6792: [ 39.923538] save_stack_trace+0x16/0x20 [ 39.927492] save_stack+0x45/0xd0 [ 39.930922] kasan_kmalloc+0xce/0xf0 [ 39.934612] kasan_slab_alloc+0xf/0x20 [ 39.938478] kmem_cache_alloc_node+0x144/0x780 [ 39.943037] __alloc_skb+0x9c/0x500 [ 39.946644] sk_stream_alloc_skb+0xb3/0x780 [ 39.950944] tcp_sendmsg_locked+0xf61/0x3200 [ 39.955328] tcp_sendmsg+0x30/0x50 [ 39.958845] inet_sendmsg+0x122/0x500 [ 39.962639] sock_sendmsg+0xce/0x110 [ 39.966329] SYSC_sendto+0x206/0x310 [ 39.970026] SyS_sendto+0x40/0x50 [ 39.973466] do_syscall_64+0x1e8/0x640 [ 39.977335] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.982499] [ 39.984104] Freed by task 6792: [ 39.987404] save_stack_trace+0x16/0x20 [ 39.991355] save_stack+0x45/0xd0 [ 39.994802] kasan_slab_free+0x75/0xc0 [ 39.998667] kmem_cache_free+0x83/0x2b0 [ 40.002618] kfree_skbmem+0x8d/0x120 [ 40.006323] __kfree_skb+0x1e/0x30 [ 40.009840] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 40.014921] tcp_sendmsg_locked+0x1ced/0x3200 [ 40.019392] tcp_sendmsg+0x30/0x50 [ 40.022909] inet_sendmsg+0x122/0x500 [ 40.026689] sock_sendmsg+0xce/0x110 [ 40.030387] SYSC_sendto+0x206/0x310 [ 40.034096] SyS_sendto+0x40/0x50 [ 40.037544] do_syscall_64+0x1e8/0x640 [ 40.041410] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 40.046576] [ 40.048193] The buggy address belongs to the object at ffff8880995f82c0 [ 40.048193] which belongs to the cache skbuff_fclone_cache of size 472 [ 40.061529] The buggy address is located 48 bytes inside of [ 40.061529] 472-byte region [ffff8880995f82c0, ffff8880995f8498) [ 40.073346] The buggy address belongs to the page: [ 40.078255] page:ffffea0002657e00 count:1 mapcount:0 mapping:ffff8880995f8040 index:0x0 [ 40.086392] flags: 0x1fffc0000000100(slab) [ 40.090615] raw: 01fffc0000000100 ffff8880995f8040 0000000000000000 0000000100000006 [ 40.098479] raw: ffffea0002a41ce0 ffff8880a9e80e48 ffff88821b7203c0 0000000000000000 [ 40.106338] page dumped because: kasan: bad access detected [ 40.112045] [ 40.114171] Memory state around the buggy address: [ 40.119077] ffff8880995f8180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 40.126941] ffff8880995f8200: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc [ 40.134281] >ffff8880995f8280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 40.142069] ^ [ 40.149303] ffff8880995f8300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.156647] ffff8880995f8380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.163983] ================================================================== [ 40.171409] Disabling lock debugging due to kernel taint [ 40.177316] Kernel panic - not syncing: panic_on_warn set ... [ 40.177316] [ 40.184681] CPU: 1 PID: 6792 Comm: syz-executor660 Tainted: G B 4.14.145 #0 [ 40.192886] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.202219] Call Trace: [ 40.204789] dump_stack+0x138/0x197 [ 40.208397] ? tcp_init_tso_segs+0x1ae/0x200 [ 40.212797] panic+0x1f2/0x426 [ 40.215968] ? add_taint.cold+0x16/0x16 [ 40.219921] ? ___preempt_schedule+0x16/0x18 [ 40.224310] kasan_end_report+0x47/0x4f [ 40.228261] kasan_report.cold+0x130/0x2af [ 40.232475] __asan_report_load2_noabort+0x14/0x20 [ 40.237382] tcp_init_tso_segs+0x1ae/0x200 [ 40.241593] ? tcp_tso_segs+0x7d/0x1c0 [ 40.245469] tcp_write_xmit+0x15e/0x4960 [ 40.250986] ? tcp_v6_md5_lookup+0x23/0x30 [ 40.255217] ? tcp_established_options+0x2c5/0x420 [ 40.260128] ? tcp_current_mss+0x1dc/0x2f0 [ 40.264351] ? __alloc_skb+0x3ee/0x500 [ 40.268219] __tcp_push_pending_frames+0xa6/0x260 [ 40.273046] tcp_send_fin+0x17e/0xc40 [ 40.276829] tcp_close+0xcc8/0xfb0 [ 40.280347] ? lock_acquire+0x16f/0x430 [ 40.284303] ? ip_mc_drop_socket+0x1d6/0x230 [ 40.288699] inet_release+0xec/0x1c0 [ 40.292392] inet6_release+0x53/0x80 [ 40.296083] __sock_release+0xce/0x2b0 [ 40.299962] ? __sock_release+0x2b0/0x2b0 [ 40.304092] sock_close+0x1b/0x30 [ 40.307525] __fput+0x275/0x7a0 [ 40.310785] ____fput+0x16/0x20 [ 40.314065] task_work_run+0x114/0x190 [ 40.317947] do_exit+0x7df/0x2c10 [ 40.321379] ? mm_update_next_owner+0x5d0/0x5d0 [ 40.326027] ? fd_install+0x4d/0x60 [ 40.329650] ? sock_map_fd+0x56/0x80 [ 40.333358] ? SyS_socket+0x103/0x170 [ 40.337137] do_group_exit+0x111/0x330 [ 40.341009] SyS_exit_group+0x1d/0x20 [ 40.345222] ? do_group_exit+0x330/0x330 [ 40.349259] do_syscall_64+0x1e8/0x640 [ 40.353123] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 40.357945] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 40.363135] RIP: 0033:0x43ee88 [ 40.366305] RSP: 002b:00007ffc7cef9bf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 40.373989] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 40.381251] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 40.388514] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 40.395770] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 40.403541] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 40.412397] Kernel Offset: disabled [ 40.416037] Rebooting in 86400 seconds..