[....] 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: [ 41.214710] random: sshd: uninitialized urandom read (32 bytes read) [ 41.477452] audit: type=1400 audit(1569053630.619:6): avc: denied { map } for pid=1767 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 [ 41.522382] random: sshd: uninitialized urandom read (32 bytes read) [ 42.111847] random: sshd: uninitialized urandom read (32 bytes read) [ 56.511646] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.211' (ECDSA) to the list of known hosts. [ 62.070571] random: sshd: uninitialized urandom read (32 bytes read) [ 62.163430] audit: type=1400 audit(1569053651.309:7): avc: denied { map } for pid=1797 comm="syz-executor255" path="/root/syz-executor255806215" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 executing program [ 63.030900] ================================================================== [ 63.038340] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 63.045084] Read of size 2 at addr ffff8881d0be67b0 by task syz-executor255/1798 [ 63.052802] [ 63.054420] CPU: 1 PID: 1798 Comm: syz-executor255 Not tainted 4.14.145+ #0 [ 63.061501] Call Trace: [ 63.064100] dump_stack+0xca/0x134 [ 63.067643] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.072035] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.076469] print_address_description+0x60/0x226 [ 63.081324] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.085734] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.090124] __kasan_report.cold+0x1a/0x41 [ 63.094370] ? kvm_guest_cpu_init+0x220/0x220 [ 63.098872] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.103282] tcp_init_tso_segs+0x19d/0x1f0 [ 63.107512] ? tcp_tso_segs+0x7b/0x1c0 [ 63.111394] tcp_write_xmit+0x15a/0x4730 [ 63.115470] ? memset+0x20/0x40 [ 63.118770] __tcp_push_pending_frames+0xa0/0x230 [ 63.123725] tcp_send_fin+0x154/0xbc0 [ 63.127529] tcp_close+0xc62/0xf40 [ 63.131091] inet_release+0xe9/0x1c0 [ 63.134795] __sock_release+0xd2/0x2c0 [ 63.138674] ? __sock_release+0x2c0/0x2c0 [ 63.142811] sock_close+0x15/0x20 [ 63.146263] __fput+0x25e/0x710 [ 63.149537] task_work_run+0x125/0x1a0 [ 63.153430] do_exit+0x9cb/0x2a20 [ 63.156881] ? mm_update_next_owner+0x610/0x610 [ 63.161550] do_group_exit+0x100/0x2e0 [ 63.165543] SyS_exit_group+0x19/0x20 [ 63.169508] ? do_group_exit+0x2e0/0x2e0 [ 63.173557] do_syscall_64+0x19b/0x520 [ 63.177470] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.182669] RIP: 0033:0x440b48 [ 63.185850] RSP: 002b:00007ffc2b8c65f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 63.194155] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b48 [ 63.201437] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 63.208791] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 63.216051] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 63.223763] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 63.231037] [ 63.232655] Allocated by task 1798: [ 63.236360] __kasan_kmalloc.part.0+0x53/0xc0 [ 63.240858] kmem_cache_alloc+0xee/0x360 [ 63.245044] __alloc_skb+0xea/0x5c0 [ 63.248665] sk_stream_alloc_skb+0xf4/0x8a0 [ 63.252994] tcp_sendmsg_locked+0xf11/0x2f50 [ 63.257402] tcp_sendmsg+0x2b/0x40 [ 63.260964] inet_sendmsg+0x15b/0x520 [ 63.264791] sock_sendmsg+0xb7/0x100 [ 63.268493] SyS_sendto+0x1de/0x2f0 [ 63.272137] do_syscall_64+0x19b/0x520 [ 63.276050] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.281263] 0xffffffffffffffff [ 63.284527] [ 63.286150] Freed by task 1798: [ 63.289421] __kasan_slab_free+0x164/0x210 [ 63.293647] kmem_cache_free+0xd7/0x3b0 [ 63.297722] kfree_skbmem+0x84/0x110 [ 63.301442] tcp_remove_empty_skb+0x264/0x320 [ 63.305925] tcp_sendmsg_locked+0x1c09/0x2f50 [ 63.310411] tcp_sendmsg+0x2b/0x40 [ 63.313951] inet_sendmsg+0x15b/0x520 [ 63.317881] sock_sendmsg+0xb7/0x100 [ 63.321609] SyS_sendto+0x1de/0x2f0 [ 63.325224] do_syscall_64+0x19b/0x520 [ 63.329099] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.334285] 0xffffffffffffffff [ 63.337546] [ 63.339156] The buggy address belongs to the object at ffff8881d0be6780 [ 63.339156] which belongs to the cache skbuff_fclone_cache of size 456 [ 63.352654] The buggy address is located 48 bytes inside of [ 63.352654] 456-byte region [ffff8881d0be6780, ffff8881d0be6948) [ 63.364767] The buggy address belongs to the page: [ 63.369805] page:ffffea000742f980 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 63.379898] flags: 0x4000000000010200(slab|head) [ 63.384648] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 63.392520] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 63.400423] page dumped because: kasan: bad access detected [ 63.406117] [ 63.407726] Memory state around the buggy address: [ 63.412655] ffff8881d0be6680: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 63.420017] ffff8881d0be6700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 63.427385] >ffff8881d0be6780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.434734] ^ [ 63.439667] ffff8881d0be6800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.447111] ffff8881d0be6880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.454540] ================================================================== [ 63.461990] Disabling lock debugging due to kernel taint [ 63.469397] Kernel panic - not syncing: panic_on_warn set ... [ 63.469397] [ 63.476780] CPU: 1 PID: 1798 Comm: syz-executor255 Tainted: G B 4.14.145+ #0 [ 63.485161] Call Trace: [ 63.487738] dump_stack+0xca/0x134 [ 63.491261] panic+0x1ea/0x3d3 [ 63.494436] ? add_taint.cold+0x16/0x16 [ 63.498407] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.502799] ? ___preempt_schedule+0x16/0x18 [ 63.507192] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.511583] end_report+0x43/0x49 [ 63.515029] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.519434] __kasan_report.cold+0xd/0x41 [ 63.523586] ? kvm_guest_cpu_init+0x220/0x220 [ 63.528150] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.532540] tcp_init_tso_segs+0x19d/0x1f0 [ 63.536768] ? tcp_tso_segs+0x7b/0x1c0 [ 63.540650] tcp_write_xmit+0x15a/0x4730 [ 63.544717] ? memset+0x20/0x40 [ 63.547995] __tcp_push_pending_frames+0xa0/0x230 [ 63.552820] tcp_send_fin+0x154/0xbc0 [ 63.556621] tcp_close+0xc62/0xf40 [ 63.560149] inet_release+0xe9/0x1c0 [ 63.563856] __sock_release+0xd2/0x2c0 [ 63.567725] ? __sock_release+0x2c0/0x2c0 [ 63.571865] sock_close+0x15/0x20 [ 63.575318] __fput+0x25e/0x710 [ 63.578580] task_work_run+0x125/0x1a0 [ 63.582452] do_exit+0x9cb/0x2a20 [ 63.585889] ? mm_update_next_owner+0x610/0x610 [ 63.590545] do_group_exit+0x100/0x2e0 [ 63.594442] SyS_exit_group+0x19/0x20 [ 63.598238] ? do_group_exit+0x2e0/0x2e0 [ 63.602349] do_syscall_64+0x19b/0x520 [ 63.606359] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.611539] RIP: 0033:0x440b48 [ 63.614726] RSP: 002b:00007ffc2b8c65f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 63.622425] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b48 [ 63.629698] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 63.636955] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 63.644209] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 63.651461] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 63.659658] Kernel Offset: 0x1d600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 63.670796] Rebooting in 86400 seconds..