[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.982879] random: sshd: uninitialized urandom read (32 bytes read) [ 32.305788] kauditd_printk_skb: 9 callbacks suppressed [ 32.305796] audit: type=1400 audit(1569027437.384:35): avc: denied { map } for pid=6753 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 [ 32.361851] random: sshd: uninitialized urandom read (32 bytes read) [ 32.860987] random: sshd: uninitialized urandom read (32 bytes read) [ 33.054793] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.49' (ECDSA) to the list of known hosts. [ 38.568281] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 38.679500] audit: type=1400 audit(1569027443.754:36): avc: denied { map } for pid=6766 comm="syz-executor442" path="/root/syz-executor442663332" 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 [ 38.707793] ================================================================== [ 38.715235] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 38.721974] Read of size 2 at addr ffff8880a1747a70 by task syz-executor442/6766 [ 38.729480] [ 38.731092] CPU: 1 PID: 6766 Comm: syz-executor442 Not tainted 4.14.145 #0 [ 38.738115] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.747446] Call Trace: [ 38.750018] dump_stack+0x138/0x197 [ 38.753631] ? migrate_misplaced_transhuge_page+0xa68/0x1ad4 [ 38.759409] ? tcp_init_tso_segs+0x1ae/0x200 [ 38.763794] print_address_description.cold+0x7c/0x1dc [ 38.769062] ? tcp_init_tso_segs+0x1ae/0x200 [ 38.773448] kasan_report.cold+0xa9/0x2af [ 38.777575] __asan_report_load2_noabort+0x14/0x20 [ 38.782492] tcp_init_tso_segs+0x1ae/0x200 [ 38.786702] ? tcp_tso_segs+0x7d/0x1c0 [ 38.790580] tcp_write_xmit+0x15e/0x4960 [ 38.794618] ? tcp_v6_md5_lookup+0x23/0x30 [ 38.798828] ? tcp_established_options+0x2c5/0x420 [ 38.803736] ? tcp_current_mss+0x1dc/0x2f0 [ 38.807950] ? __alloc_skb+0x3ee/0x500 [ 38.811831] __tcp_push_pending_frames+0xa6/0x260 [ 38.816654] tcp_send_fin+0x17e/0xc40 [ 38.820431] tcp_close+0xcc8/0xfb0 [ 38.823945] ? lock_acquire+0x16f/0x430 [ 38.827898] ? ip_mc_drop_socket+0x1d6/0x230 [ 38.832367] inet_release+0xec/0x1c0 [ 38.836061] inet6_release+0x53/0x80 [ 38.839754] __sock_release+0xce/0x2b0 [ 38.843620] ? __sock_release+0x2b0/0x2b0 [ 38.847742] sock_close+0x1b/0x30 [ 38.851172] __fput+0x275/0x7a0 [ 38.854447] ____fput+0x16/0x20 [ 38.857704] task_work_run+0x114/0x190 [ 38.861571] do_exit+0x7df/0x2c10 [ 38.865017] ? mm_update_next_owner+0x5d0/0x5d0 [ 38.869663] ? fd_install+0x4d/0x60 [ 38.873266] ? sock_map_fd+0x56/0x80 [ 38.876955] ? SyS_socket+0x103/0x170 [ 38.880734] do_group_exit+0x111/0x330 [ 38.884596] SyS_exit_group+0x1d/0x20 [ 38.888371] ? do_group_exit+0x330/0x330 [ 38.892409] do_syscall_64+0x1e8/0x640 [ 38.896274] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 38.901108] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.906275] RIP: 0033:0x43ee88 [ 38.909441] RSP: 002b:00007fffc6a7d228 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 38.917126] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 38.924374] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 38.931625] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 38.938883] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 38.946129] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 38.953384] [ 38.954990] Allocated by task 6766: [ 38.961026] save_stack_trace+0x16/0x20 [ 38.964990] save_stack+0x45/0xd0 [ 38.968416] kasan_kmalloc+0xce/0xf0 [ 38.972106] kasan_slab_alloc+0xf/0x20 [ 38.975971] kmem_cache_alloc_node+0x144/0x780 [ 38.980528] __alloc_skb+0x9c/0x500 [ 38.984130] sk_stream_alloc_skb+0xb3/0x780 [ 38.988426] tcp_sendmsg_locked+0xf61/0x3200 [ 38.992808] tcp_sendmsg+0x30/0x50 [ 38.996323] inet_sendmsg+0x122/0x500 [ 39.000101] sock_sendmsg+0xce/0x110 [ 39.003790] SYSC_sendto+0x206/0x310 [ 39.007476] SyS_sendto+0x40/0x50 [ 39.010907] do_syscall_64+0x1e8/0x640 [ 39.014770] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.019932] [ 39.021540] Freed by task 6766: [ 39.024798] save_stack_trace+0x16/0x20 [ 39.028747] save_stack+0x45/0xd0 [ 39.032178] kasan_slab_free+0x75/0xc0 [ 39.036058] kmem_cache_free+0x83/0x2b0 [ 39.040009] kfree_skbmem+0x8d/0x120 [ 39.043705] __kfree_skb+0x1e/0x30 [ 39.047219] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 39.052297] tcp_sendmsg_locked+0x1ced/0x3200 [ 39.056766] tcp_sendmsg+0x30/0x50 [ 39.060279] inet_sendmsg+0x122/0x500 [ 39.064052] sock_sendmsg+0xce/0x110 [ 39.067754] SYSC_sendto+0x206/0x310 [ 39.071444] SyS_sendto+0x40/0x50 [ 39.074875] do_syscall_64+0x1e8/0x640 [ 39.078837] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.083999] [ 39.086300] The buggy address belongs to the object at ffff8880a1747a40 [ 39.086300] which belongs to the cache skbuff_fclone_cache of size 472 [ 39.099628] The buggy address is located 48 bytes inside of [ 39.099628] 472-byte region [ffff8880a1747a40, ffff8880a1747c18) [ 39.111388] The buggy address belongs to the page: [ 39.116380] page:ffffea000285d1c0 count:1 mapcount:0 mapping:ffff8880a1747040 index:0x0 [ 39.124499] flags: 0x1fffc0000000100(slab) [ 39.128708] raw: 01fffc0000000100 ffff8880a1747040 0000000000000000 0000000100000006 [ 39.136563] raw: ffffea0002645120 ffff8880a9e1bd48 ffff88821b75f3c0 0000000000000000 [ 39.144416] page dumped because: kasan: bad access detected [ 39.150113] [ 39.151717] Memory state around the buggy address: [ 39.156619] ffff8880a1747900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 39.163952] ffff8880a1747980: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc [ 39.171286] >ffff8880a1747a00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 39.178622] ^ [ 39.185609] ffff8880a1747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.192943] ffff8880a1747b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.200915] ================================================================== [ 39.208271] Disabling lock debugging due to kernel taint [ 39.214430] Kernel panic - not syncing: panic_on_warn set ... [ 39.214430] [ 39.221810] CPU: 1 PID: 6766 Comm: syz-executor442 Tainted: G B 4.14.145 #0 [ 39.230019] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.239403] Call Trace: [ 39.241974] dump_stack+0x138/0x197 [ 39.245581] ? tcp_init_tso_segs+0x1ae/0x200 [ 39.249966] panic+0x1f2/0x426 [ 39.253181] ? add_taint.cold+0x16/0x16 [ 39.257140] ? ___preempt_schedule+0x16/0x18 [ 39.261528] kasan_end_report+0x47/0x4f [ 39.265479] kasan_report.cold+0x130/0x2af [ 39.269689] __asan_report_load2_noabort+0x14/0x20 [ 39.274593] tcp_init_tso_segs+0x1ae/0x200 [ 39.278802] ? tcp_tso_segs+0x7d/0x1c0 [ 39.282691] tcp_write_xmit+0x15e/0x4960 [ 39.286779] ? tcp_v6_md5_lookup+0x23/0x30 [ 39.290995] ? tcp_established_options+0x2c5/0x420 [ 39.295932] ? tcp_current_mss+0x1dc/0x2f0 [ 39.300151] ? __alloc_skb+0x3ee/0x500 [ 39.304073] __tcp_push_pending_frames+0xa6/0x260 [ 39.308895] tcp_send_fin+0x17e/0xc40 [ 39.312671] tcp_close+0xcc8/0xfb0 [ 39.316188] ? lock_acquire+0x16f/0x430 [ 39.320137] ? ip_mc_drop_socket+0x1d6/0x230 [ 39.324524] inet_release+0xec/0x1c0 [ 39.328302] inet6_release+0x53/0x80 [ 39.331992] __sock_release+0xce/0x2b0 [ 39.335854] ? __sock_release+0x2b0/0x2b0 [ 39.339976] sock_close+0x1b/0x30 [ 39.343404] __fput+0x275/0x7a0 [ 39.346732] ____fput+0x16/0x20 [ 39.349997] task_work_run+0x114/0x190 [ 39.353880] do_exit+0x7df/0x2c10 [ 39.357333] ? mm_update_next_owner+0x5d0/0x5d0 [ 39.362017] ? fd_install+0x4d/0x60 [ 39.365626] ? sock_map_fd+0x56/0x80 [ 39.369317] ? SyS_socket+0x103/0x170 [ 39.373094] do_group_exit+0x111/0x330 [ 39.376958] SyS_exit_group+0x1d/0x20 [ 39.380734] ? do_group_exit+0x330/0x330 [ 39.384770] do_syscall_64+0x1e8/0x640 [ 39.388643] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 39.393465] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.398632] RIP: 0033:0x43ee88 [ 39.401798] RSP: 002b:00007fffc6a7d228 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 39.409479] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 39.416726] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 39.424060] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 39.431307] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 39.438565] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 39.447287] Kernel Offset: disabled [ 39.450913] Rebooting in 86400 seconds..