[....] 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: [ 26.409468] random: sshd: uninitialized urandom read (32 bytes read) [ 26.695124] audit: type=1400 audit(1569018366.950:6): avc: denied { map } for pid=1763 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 [ 26.746679] random: sshd: uninitialized urandom read (32 bytes read) [ 27.259828] random: sshd: uninitialized urandom read (32 bytes read) [ 27.419678] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.17' (ECDSA) to the list of known hosts. [ 32.975208] random: sshd: uninitialized urandom read (32 bytes read) [ 33.076760] audit: type=1400 audit(1569018373.330:7): avc: denied { map } for pid=1781 comm="syz-executor109" path="/root/syz-executor109248848" dev="sda1" ino=16461 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 [ 33.921182] ================================================================== [ 33.930232] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 33.938392] Read of size 2 at addr ffff8881cd0f8030 by task syz-executor109/1782 [ 33.948711] [ 33.950585] CPU: 0 PID: 1782 Comm: syz-executor109 Not tainted 4.14.145+ #0 [ 33.959527] Call Trace: [ 33.964725] dump_stack+0xca/0x134 [ 33.969105] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.974229] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.980209] print_address_description+0x60/0x226 [ 33.986289] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.991312] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.996418] __kasan_report.cold+0x1a/0x41 [ 34.000666] ? kvm_guest_cpu_init+0x220/0x220 [ 34.005999] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.010901] tcp_init_tso_segs+0x19d/0x1f0 [ 34.015137] ? tcp_tso_segs+0x7b/0x1c0 [ 34.019112] tcp_write_xmit+0x15a/0x4730 [ 34.023711] ? memset+0x20/0x40 [ 34.027499] __tcp_push_pending_frames+0xa0/0x230 [ 34.033070] tcp_send_fin+0x154/0xbc0 [ 34.038247] tcp_close+0xc62/0xf40 [ 34.042603] inet_release+0xe9/0x1c0 [ 34.046583] __sock_release+0xd2/0x2c0 [ 34.050582] ? __sock_release+0x2c0/0x2c0 [ 34.054824] sock_close+0x15/0x20 [ 34.059507] __fput+0x25e/0x710 [ 34.063849] task_work_run+0x125/0x1a0 [ 34.068135] do_exit+0x9cb/0x2a20 [ 34.072570] ? mm_update_next_owner+0x610/0x610 [ 34.079429] do_group_exit+0x100/0x2e0 [ 34.084721] SyS_exit_group+0x19/0x20 [ 34.088903] ? do_group_exit+0x2e0/0x2e0 [ 34.093452] do_syscall_64+0x19b/0x520 [ 34.098289] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.104242] RIP: 0033:0x440b58 [ 34.108216] RSP: 002b:00007ffe158e99f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 34.116653] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b58 [ 34.124934] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 34.133262] RBP: 00000000004c6ff0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 34.143736] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 34.152354] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 34.162070] [ 34.164083] Allocated by task 1782: [ 34.167996] __kasan_kmalloc.part.0+0x53/0xc0 [ 34.173054] kmem_cache_alloc+0xee/0x360 [ 34.178455] __alloc_skb+0xea/0x5c0 [ 34.182779] sk_stream_alloc_skb+0xf4/0x8a0 [ 34.188630] tcp_sendmsg_locked+0xf11/0x2f50 [ 34.194266] tcp_sendmsg+0x2b/0x40 [ 34.198941] inet_sendmsg+0x15b/0x520 [ 34.203789] sock_sendmsg+0xb7/0x100 [ 34.208220] SyS_sendto+0x1de/0x2f0 [ 34.212635] do_syscall_64+0x19b/0x520 [ 34.216923] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.224321] 0xffffffffffffffff [ 34.228017] [ 34.229762] Freed by task 1782: [ 34.233614] __kasan_slab_free+0x164/0x210 [ 34.238449] kmem_cache_free+0xd7/0x3b0 [ 34.242827] kfree_skbmem+0x84/0x110 [ 34.247338] tcp_remove_empty_skb+0x264/0x320 [ 34.253332] tcp_sendmsg_locked+0x1c09/0x2f50 [ 34.258505] tcp_sendmsg+0x2b/0x40 [ 34.263593] inet_sendmsg+0x15b/0x520 [ 34.267808] sock_sendmsg+0xb7/0x100 [ 34.271884] SyS_sendto+0x1de/0x2f0 [ 34.275601] do_syscall_64+0x19b/0x520 [ 34.280802] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.286813] 0xffffffffffffffff [ 34.291162] [ 34.292991] The buggy address belongs to the object at ffff8881cd0f8000 [ 34.292991] which belongs to the cache skbuff_fclone_cache of size 456 [ 34.307372] The buggy address is located 48 bytes inside of [ 34.307372] 456-byte region [ffff8881cd0f8000, ffff8881cd0f81c8) [ 34.321292] The buggy address belongs to the page: [ 34.327757] page:ffffea0007343e00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 34.338843] flags: 0x4000000000010200(slab|head) [ 34.344616] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 34.354516] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 34.363815] page dumped because: kasan: bad access detected [ 34.371053] [ 34.372883] Memory state around the buggy address: [ 34.378668] ffff8881cd0f7f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 34.387466] ffff8881cd0f7f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 34.395204] >ffff8881cd0f8000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.403426] ^ [ 34.409032] ffff8881cd0f8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.417833] ffff8881cd0f8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.426592] ================================================================== [ 34.435142] Disabling lock debugging due to kernel taint [ 34.441859] Kernel panic - not syncing: panic_on_warn set ... [ 34.441859] [ 34.450578] CPU: 0 PID: 1782 Comm: syz-executor109 Tainted: G B 4.14.145+ #0 [ 34.459977] Call Trace: [ 34.462716] dump_stack+0xca/0x134 [ 34.466824] panic+0x1ea/0x3d3 [ 34.471154] ? add_taint.cold+0x16/0x16 [ 34.475306] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.480224] ? ___preempt_schedule+0x16/0x18 [ 34.485380] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.490144] end_report+0x43/0x49 [ 34.493702] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.498318] __kasan_report.cold+0xd/0x41 [ 34.502642] ? kvm_guest_cpu_init+0x220/0x220 [ 34.507768] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.513893] tcp_init_tso_segs+0x19d/0x1f0 [ 34.518696] ? tcp_tso_segs+0x7b/0x1c0 [ 34.522735] tcp_write_xmit+0x15a/0x4730 [ 34.527620] ? memset+0x20/0x40 [ 34.531374] __tcp_push_pending_frames+0xa0/0x230 [ 34.536802] tcp_send_fin+0x154/0xbc0 [ 34.541103] tcp_close+0xc62/0xf40 [ 34.545506] inet_release+0xe9/0x1c0 [ 34.549461] __sock_release+0xd2/0x2c0 [ 34.553684] ? __sock_release+0x2c0/0x2c0 [ 34.558247] sock_close+0x15/0x20 [ 34.561904] __fput+0x25e/0x710 [ 34.565494] task_work_run+0x125/0x1a0 [ 34.569584] do_exit+0x9cb/0x2a20 [ 34.573199] ? mm_update_next_owner+0x610/0x610 [ 34.578350] do_group_exit+0x100/0x2e0 [ 34.582627] SyS_exit_group+0x19/0x20 [ 34.586986] ? do_group_exit+0x2e0/0x2e0 [ 34.591514] do_syscall_64+0x19b/0x520 [ 34.595708] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.601375] RIP: 0033:0x440b58 [ 34.606474] RSP: 002b:00007ffe158e99f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 34.615131] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b58 [ 34.623344] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 34.631136] RBP: 00000000004c6ff0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 34.639448] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 34.649100] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 34.659116] Kernel Offset: 0x15400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 34.671950] Rebooting in 86400 seconds..