[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 61.120479] random: sshd: uninitialized urandom read (32 bytes read) [ 61.601074] audit: type=1400 audit(1569034361.034:6): avc: denied { map } for pid=1795 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 [ 61.649931] random: sshd: uninitialized urandom read (32 bytes read) [ 62.148746] random: sshd: uninitialized urandom read (32 bytes read) [ 62.298643] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.151' (ECDSA) to the list of known hosts. [ 67.769187] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 67.860841] audit: type=1400 audit(1569034367.294:7): avc: denied { map } for pid=1807 comm="syz-executor992" path="/root/syz-executor992080323" 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 [ 67.890717] ================================================================== [ 67.898237] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 67.904968] Read of size 2 at addr ffff8881c59cccb0 by task syz-executor992/1807 [ 67.912514] [ 67.914122] CPU: 0 PID: 1807 Comm: syz-executor992 Not tainted 4.14.145+ #0 [ 67.921195] Call Trace: [ 67.923768] dump_stack+0xca/0x134 [ 67.927319] ? tcp_init_tso_segs+0x19d/0x1f0 [ 67.931861] ? tcp_init_tso_segs+0x19d/0x1f0 [ 67.936242] print_address_description+0x60/0x226 [ 67.941133] ? tcp_init_tso_segs+0x19d/0x1f0 [ 67.945516] ? tcp_init_tso_segs+0x19d/0x1f0 [ 67.949900] __kasan_report.cold+0x1a/0x41 [ 67.954117] ? kvm_guest_cpu_init+0x220/0x220 [ 67.958584] ? tcp_init_tso_segs+0x19d/0x1f0 [ 67.962971] tcp_init_tso_segs+0x19d/0x1f0 [ 67.967181] ? tcp_tso_segs+0x7b/0x1c0 [ 67.971048] tcp_write_xmit+0x15a/0x4730 [ 67.975090] ? ip6_mtu+0x206/0x330 [ 67.978606] ? lock_downgrade+0x5d0/0x5d0 [ 67.982732] ? lock_acquire+0x12b/0x360 [ 67.986689] __tcp_push_pending_frames+0xa0/0x230 [ 67.991507] tcp_send_fin+0x154/0xbc0 [ 67.995287] tcp_close+0xc62/0xf40 [ 67.998802] ? lock_acquire+0x12b/0x360 [ 68.002754] ? __sock_release+0x86/0x2c0 [ 68.006794] inet_release+0xe9/0x1c0 [ 68.010487] inet6_release+0x4c/0x70 [ 68.014309] __sock_release+0xd2/0x2c0 [ 68.018173] ? __sock_release+0x2c0/0x2c0 [ 68.022333] sock_close+0x15/0x20 [ 68.025784] __fput+0x25e/0x710 [ 68.029045] task_work_run+0x125/0x1a0 [ 68.032918] do_exit+0x9cb/0x2a20 [ 68.036350] ? mm_update_next_owner+0x610/0x610 [ 68.041007] do_group_exit+0x100/0x2e0 [ 68.044875] SyS_exit_group+0x19/0x20 [ 68.048653] ? do_group_exit+0x2e0/0x2e0 [ 68.052690] do_syscall_64+0x19b/0x520 [ 68.056560] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 68.061841] RIP: 0033:0x43ee58 [ 68.065006] RSP: 002b:00007ffd097d7608 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 68.072703] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee58 [ 68.079948] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 68.087196] RBP: 00000000004be668 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 68.094443] R10: 0000000020000008 R11: 0000000000000246 R12: 0000000000000001 [ 68.101700] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 68.108959] [ 68.110564] Allocated by task 1807: [ 68.114173] __kasan_kmalloc.part.0+0x53/0xc0 [ 68.118648] kmem_cache_alloc+0xee/0x360 [ 68.122703] __alloc_skb+0xea/0x5c0 [ 68.126328] sk_stream_alloc_skb+0xf4/0x8a0 [ 68.130626] tcp_sendmsg_locked+0xf11/0x2f50 [ 68.135009] tcp_sendmsg+0x2b/0x40 [ 68.138534] inet_sendmsg+0x15b/0x520 [ 68.142310] sock_sendmsg+0xb7/0x100 [ 68.146000] SyS_sendto+0x1de/0x2f0 [ 68.149599] do_syscall_64+0x19b/0x520 [ 68.153473] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 68.158635] 0xffffffffffffffff [ 68.161899] [ 68.163500] Freed by task 1807: [ 68.166764] __kasan_slab_free+0x164/0x210 [ 68.170974] kmem_cache_free+0xd7/0x3b0 [ 68.174931] kfree_skbmem+0x84/0x110 [ 68.178624] tcp_remove_empty_skb+0x264/0x320 [ 68.183094] tcp_sendmsg_locked+0x1c09/0x2f50 [ 68.187564] tcp_sendmsg+0x2b/0x40 [ 68.191080] inet_sendmsg+0x15b/0x520 [ 68.194856] sock_sendmsg+0xb7/0x100 [ 68.198542] SyS_sendto+0x1de/0x2f0 [ 68.202143] do_syscall_64+0x19b/0x520 [ 68.206005] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 68.211171] 0xffffffffffffffff [ 68.214436] [ 68.216057] The buggy address belongs to the object at ffff8881c59ccc80 [ 68.216057] which belongs to the cache skbuff_fclone_cache of size 456 [ 68.229383] The buggy address is located 48 bytes inside of [ 68.229383] 456-byte region [ffff8881c59ccc80, ffff8881c59cce48) [ 68.241145] The buggy address belongs to the page: [ 68.246056] page:ffffea0007167300 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 68.256009] flags: 0x4000000000010200(slab|head) [ 68.260743] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 68.268599] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 68.276457] page dumped because: kasan: bad access detected [ 68.282137] [ 68.283740] Memory state around the buggy address: [ 68.288645] ffff8881c59ccb80: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 68.295978] ffff8881c59ccc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 68.303320] >ffff8881c59ccc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 68.310652] ^ [ 68.315555] ffff8881c59ccd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 68.322891] ffff8881c59ccd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 68.330224] ================================================================== [ 68.337556] Disabling lock debugging due to kernel taint [ 68.343366] Kernel panic - not syncing: panic_on_warn set ... [ 68.343366] [ 68.350742] CPU: 0 PID: 1807 Comm: syz-executor992 Tainted: G B 4.14.145+ #0 [ 68.359034] Call Trace: [ 68.361610] dump_stack+0xca/0x134 [ 68.365128] panic+0x1ea/0x3d3 [ 68.368293] ? add_taint.cold+0x16/0x16 [ 68.372244] ? tcp_init_tso_segs+0x19d/0x1f0 [ 68.376624] ? ___preempt_schedule+0x16/0x18 [ 68.381008] ? tcp_init_tso_segs+0x19d/0x1f0 [ 68.385389] end_report+0x43/0x49 [ 68.388816] ? tcp_init_tso_segs+0x19d/0x1f0 [ 68.393195] __kasan_report.cold+0xd/0x41 [ 68.397319] ? kvm_guest_cpu_init+0x220/0x220 [ 68.401785] ? tcp_init_tso_segs+0x19d/0x1f0 [ 68.406190] tcp_init_tso_segs+0x19d/0x1f0 [ 68.410399] ? tcp_tso_segs+0x7b/0x1c0 [ 68.414262] tcp_write_xmit+0x15a/0x4730 [ 68.418296] ? ip6_mtu+0x206/0x330 [ 68.421819] ? lock_downgrade+0x5d0/0x5d0 [ 68.425939] ? lock_acquire+0x12b/0x360 [ 68.429892] __tcp_push_pending_frames+0xa0/0x230 [ 68.434710] tcp_send_fin+0x154/0xbc0 [ 68.438484] tcp_close+0xc62/0xf40 [ 68.441997] ? lock_acquire+0x12b/0x360 [ 68.445945] ? __sock_release+0x86/0x2c0 [ 68.449981] inet_release+0xe9/0x1c0 [ 68.453671] inet6_release+0x4c/0x70 [ 68.457369] __sock_release+0xd2/0x2c0 [ 68.461232] ? __sock_release+0x2c0/0x2c0 [ 68.465352] sock_close+0x15/0x20 [ 68.468778] __fput+0x25e/0x710 [ 68.472036] task_work_run+0x125/0x1a0 [ 68.475900] do_exit+0x9cb/0x2a20 [ 68.479332] ? mm_update_next_owner+0x610/0x610 [ 68.483980] do_group_exit+0x100/0x2e0 [ 68.487840] SyS_exit_group+0x19/0x20 [ 68.491614] ? do_group_exit+0x2e0/0x2e0 [ 68.495647] do_syscall_64+0x19b/0x520 [ 68.499512] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 68.504675] RIP: 0033:0x43ee58 [ 68.507837] RSP: 002b:00007ffd097d7608 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 68.515517] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee58 [ 68.522760] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 68.530005] RBP: 00000000004be668 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 68.537260] R10: 0000000020000008 R11: 0000000000000246 R12: 0000000000000001 [ 68.544502] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 68.552236] Kernel Offset: 0x23600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 68.563146] Rebooting in 86400 seconds..