[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 32.055819] random: sshd: uninitialized urandom read (32 bytes read) [ 32.293182] kauditd_printk_skb: 9 callbacks suppressed [ 32.293190] audit: type=1400 audit(1569017041.217:35): avc: denied { map } for pid=6840 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 [ 32.347384] random: sshd: uninitialized urandom read (32 bytes read) [ 32.880322] random: sshd: uninitialized urandom read (32 bytes read) [ 36.581987] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.14' (ECDSA) to the list of known hosts. [ 42.128442] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 42.239937] audit: type=1400 audit(1569017051.157:36): avc: denied { map } for pid=6853 comm="syz-executor088" path="/root/syz-executor088817303" 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 [ 42.268259] ================================================================== [ 42.275669] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 42.282398] Read of size 2 at addr ffff88809dd93a70 by task syz-executor088/6853 [ 42.289948] [ 42.291559] CPU: 0 PID: 6853 Comm: syz-executor088 Not tainted 4.14.145 #0 [ 42.298543] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.307876] Call Trace: [ 42.310444] dump_stack+0x138/0x197 [ 42.314050] ? tcp_init_tso_segs+0x1ae/0x200 [ 42.318435] print_address_description.cold+0x7c/0x1dc [ 42.323687] ? tcp_init_tso_segs+0x1ae/0x200 [ 42.328072] kasan_report.cold+0xa9/0x2af [ 42.332198] __asan_report_load2_noabort+0x14/0x20 [ 42.337158] tcp_init_tso_segs+0x1ae/0x200 [ 42.341387] ? tcp_tso_segs+0x7d/0x1c0 [ 42.345254] tcp_write_xmit+0x15e/0x4960 [ 42.349291] ? tcp_v6_md5_lookup+0x23/0x30 [ 42.353522] ? tcp_established_options+0x2c5/0x420 [ 42.358428] ? tcp_current_mss+0x1dc/0x2f0 [ 42.362641] ? __alloc_skb+0x3ee/0x500 [ 42.366507] __tcp_push_pending_frames+0xa6/0x260 [ 42.371326] tcp_send_fin+0x17e/0xc40 [ 42.375118] tcp_close+0xcc8/0xfb0 [ 42.378634] ? lock_acquire+0x16f/0x430 [ 42.382584] ? ip_mc_drop_socket+0x1d6/0x230 [ 42.386972] inet_release+0xec/0x1c0 [ 42.390661] inet6_release+0x53/0x80 [ 42.394368] __sock_release+0xce/0x2b0 [ 42.398244] ? __sock_release+0x2b0/0x2b0 [ 42.402409] sock_close+0x1b/0x30 [ 42.405842] __fput+0x275/0x7a0 [ 42.409138] ____fput+0x16/0x20 [ 42.412418] task_work_run+0x114/0x190 [ 42.416298] do_exit+0x7df/0x2c10 [ 42.419738] ? mm_update_next_owner+0x5d0/0x5d0 [ 42.424396] ? fd_install+0x4d/0x60 [ 42.428012] ? sock_map_fd+0x56/0x80 [ 42.431705] ? SyS_socket+0x103/0x170 [ 42.435506] do_group_exit+0x111/0x330 [ 42.439370] SyS_exit_group+0x1d/0x20 [ 42.443146] ? do_group_exit+0x330/0x330 [ 42.447183] do_syscall_64+0x1e8/0x640 [ 42.451045] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 42.455866] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.461042] RIP: 0033:0x43ee88 [ 42.464208] RSP: 002b:00007ffdfe9e0998 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 42.471890] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 42.479135] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 42.486379] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 42.493624] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 42.500877] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 42.508131] [ 42.509733] Allocated by task 6853: [ 42.513349] save_stack_trace+0x16/0x20 [ 42.517298] save_stack+0x45/0xd0 [ 42.520724] kasan_kmalloc+0xce/0xf0 [ 42.524412] kasan_slab_alloc+0xf/0x20 [ 42.528277] kmem_cache_alloc_node+0x144/0x780 [ 42.532835] __alloc_skb+0x9c/0x500 [ 42.536435] sk_stream_alloc_skb+0xb3/0x780 [ 42.540733] tcp_sendmsg_locked+0xf61/0x3200 [ 42.545114] tcp_sendmsg+0x30/0x50 [ 42.548631] inet_sendmsg+0x122/0x500 [ 42.552408] sock_sendmsg+0xce/0x110 [ 42.556095] SYSC_sendto+0x206/0x310 [ 42.559786] SyS_sendto+0x40/0x50 [ 42.563227] do_syscall_64+0x1e8/0x640 [ 42.567089] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.572249] [ 42.573851] Freed by task 6853: [ 42.577105] save_stack_trace+0x16/0x20 [ 42.581067] save_stack+0x45/0xd0 [ 42.584496] kasan_slab_free+0x75/0xc0 [ 42.588357] kmem_cache_free+0x83/0x2b0 [ 42.592306] kfree_skbmem+0x8d/0x120 [ 42.595993] __kfree_skb+0x1e/0x30 [ 42.599507] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 42.604583] tcp_sendmsg_locked+0x1ced/0x3200 [ 42.609054] tcp_sendmsg+0x30/0x50 [ 42.612569] inet_sendmsg+0x122/0x500 [ 42.616349] sock_sendmsg+0xce/0x110 [ 42.620043] SYSC_sendto+0x206/0x310 [ 42.623732] SyS_sendto+0x40/0x50 [ 42.627161] do_syscall_64+0x1e8/0x640 [ 42.631026] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.636189] [ 42.637796] The buggy address belongs to the object at ffff88809dd93a40 [ 42.637796] which belongs to the cache skbuff_fclone_cache of size 472 [ 42.651160] The buggy address is located 48 bytes inside of [ 42.651160] 472-byte region [ffff88809dd93a40, ffff88809dd93c18) [ 42.662962] The buggy address belongs to the page: [ 42.667905] page:ffffea00027764c0 count:1 mapcount:0 mapping:ffff88809dd93040 index:0x0 [ 42.676045] flags: 0x1fffc0000000100(slab) [ 42.680258] raw: 01fffc0000000100 ffff88809dd93040 0000000000000000 0000000100000006 [ 42.688114] raw: ffffea00025389a0 ffff8880a9e80e48 ffff8880a9e82d80 0000000000000000 [ 42.695968] page dumped because: kasan: bad access detected [ 42.701652] [ 42.703252] Memory state around the buggy address: [ 42.708165] ffff88809dd93900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 42.715502] ffff88809dd93980: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc [ 42.722836] >ffff88809dd93a00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 42.730182] ^ [ 42.737181] ffff88809dd93a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.744517] ffff88809dd93b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.751849] ================================================================== [ 42.759180] Disabling lock debugging due to kernel taint [ 42.766729] Kernel panic - not syncing: panic_on_warn set ... [ 42.766729] [ 42.774088] CPU: 0 PID: 6853 Comm: syz-executor088 Tainted: G B 4.14.145 #0 [ 42.782292] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.791620] Call Trace: [ 42.794189] dump_stack+0x138/0x197 [ 42.797795] ? tcp_init_tso_segs+0x1ae/0x200 [ 42.802195] panic+0x1f2/0x426 [ 42.805372] ? add_taint.cold+0x16/0x16 [ 42.809322] ? ___preempt_schedule+0x16/0x18 [ 42.813707] kasan_end_report+0x47/0x4f [ 42.817654] kasan_report.cold+0x130/0x2af [ 42.821878] __asan_report_load2_noabort+0x14/0x20 [ 42.826787] tcp_init_tso_segs+0x1ae/0x200 [ 42.830996] ? tcp_tso_segs+0x7d/0x1c0 [ 42.834862] tcp_write_xmit+0x15e/0x4960 [ 42.838900] ? tcp_v6_md5_lookup+0x23/0x30 [ 42.843109] ? tcp_established_options+0x2c5/0x420 [ 42.848038] ? tcp_current_mss+0x1dc/0x2f0 [ 42.852251] ? __alloc_skb+0x3ee/0x500 [ 42.856113] __tcp_push_pending_frames+0xa6/0x260 [ 42.860931] tcp_send_fin+0x17e/0xc40 [ 42.864732] tcp_close+0xcc8/0xfb0 [ 42.868256] ? lock_acquire+0x16f/0x430 [ 42.872209] ? ip_mc_drop_socket+0x1d6/0x230 [ 42.876594] inet_release+0xec/0x1c0 [ 42.880280] inet6_release+0x53/0x80 [ 42.883979] __sock_release+0xce/0x2b0 [ 42.887842] ? __sock_release+0x2b0/0x2b0 [ 42.891962] sock_close+0x1b/0x30 [ 42.895399] __fput+0x275/0x7a0 [ 42.898658] ____fput+0x16/0x20 [ 42.901911] task_work_run+0x114/0x190 [ 42.905774] do_exit+0x7df/0x2c10 [ 42.909202] ? mm_update_next_owner+0x5d0/0x5d0 [ 42.913848] ? fd_install+0x4d/0x60 [ 42.917449] ? sock_map_fd+0x56/0x80 [ 42.921137] ? SyS_socket+0x103/0x170 [ 42.924927] do_group_exit+0x111/0x330 [ 42.928790] SyS_exit_group+0x1d/0x20 [ 42.932563] ? do_group_exit+0x330/0x330 [ 42.936599] do_syscall_64+0x1e8/0x640 [ 42.940459] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 42.945279] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.950452] RIP: 0033:0x43ee88 [ 42.953618] RSP: 002b:00007ffdfe9e0998 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 42.961299] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 42.968560] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 42.975804] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 42.983050] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 42.990304] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 42.998808] Kernel Offset: disabled [ 43.002433] Rebooting in 86400 seconds..