[....] Starting OpenBSD Secure Shell server: sshd[ 12.014040] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 30.134421] random: sshd: uninitialized urandom read (32 bytes read) [ 30.658513] audit: type=1400 audit(1569088061.776:6): avc: denied { map } for pid=1770 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 [ 30.694015] random: sshd: uninitialized urandom read (32 bytes read) [ 31.287369] random: sshd: uninitialized urandom read (32 bytes read) [ 31.452040] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.6' (ECDSA) to the list of known hosts. [ 36.882247] random: sshd: uninitialized urandom read (32 bytes read) [ 36.989143] audit: type=1400 audit(1569088068.106:7): avc: denied { map } for pid=1789 comm="syz-executor280" path="/root/syz-executor280505764" 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 executing program [ 37.820776] ================================================================== [ 37.828335] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 37.835063] Read of size 2 at addr ffff8881d6fb5430 by task syz-executor280/1790 [ 37.842572] [ 37.844202] CPU: 0 PID: 1790 Comm: syz-executor280 Not tainted 4.14.145+ #0 [ 37.851278] Call Trace: [ 37.853849] dump_stack+0xca/0x134 [ 37.857374] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.861758] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.866318] print_address_description+0x60/0x226 [ 37.871146] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.875531] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.879915] __kasan_report.cold+0x1a/0x41 [ 37.884139] ? kvm_guest_cpu_init+0x220/0x220 [ 37.888616] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.893006] tcp_init_tso_segs+0x19d/0x1f0 [ 37.897220] ? tcp_tso_segs+0x7b/0x1c0 [ 37.901085] tcp_write_xmit+0x15a/0x4730 [ 37.905126] ? memset+0x20/0x40 [ 37.908418] __tcp_push_pending_frames+0xa0/0x230 [ 37.913240] tcp_send_fin+0x154/0xbc0 [ 37.917025] tcp_close+0xc62/0xf40 [ 37.920551] inet_release+0xe9/0x1c0 [ 37.924269] __sock_release+0xd2/0x2c0 [ 37.928239] ? __sock_release+0x2c0/0x2c0 [ 37.932380] sock_close+0x15/0x20 [ 37.935831] __fput+0x25e/0x710 [ 37.939110] task_work_run+0x125/0x1a0 [ 37.942992] do_exit+0x9cb/0x2a20 [ 37.946432] ? mm_update_next_owner+0x610/0x610 [ 37.951277] do_group_exit+0x100/0x2e0 [ 37.955153] SyS_exit_group+0x19/0x20 [ 37.958929] ? do_group_exit+0x2e0/0x2e0 [ 37.962974] do_syscall_64+0x19b/0x520 [ 37.966902] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 37.972074] RIP: 0033:0x440b38 [ 37.975252] RSP: 002b:00007ffe01a9f9e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 37.982950] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b38 [ 37.990207] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 37.997467] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 38.004763] R10: 0000000020000804 R11: 0000000000000246 R12: 0000000000000001 [ 38.012024] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 38.019285] [ 38.020898] Allocated by task 1790: [ 38.024511] __kasan_kmalloc.part.0+0x53/0xc0 [ 38.028984] kmem_cache_alloc+0xee/0x360 [ 38.033108] __alloc_skb+0xea/0x5c0 [ 38.036711] sk_stream_alloc_skb+0xf4/0x8a0 [ 38.041018] tcp_sendmsg_locked+0xf11/0x2f50 [ 38.045401] tcp_sendmsg+0x2b/0x40 [ 38.048919] inet_sendmsg+0x15b/0x520 [ 38.052739] sock_sendmsg+0xb7/0x100 [ 38.056428] SyS_sendto+0x1de/0x2f0 [ 38.060031] do_syscall_64+0x19b/0x520 [ 38.063896] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.069059] 0xffffffffffffffff [ 38.072318] [ 38.073930] Freed by task 1790: [ 38.077195] __kasan_slab_free+0x164/0x210 [ 38.081416] kmem_cache_free+0xd7/0x3b0 [ 38.085371] kfree_skbmem+0x84/0x110 [ 38.089071] tcp_remove_empty_skb+0x264/0x320 [ 38.093543] tcp_sendmsg_locked+0x1c09/0x2f50 [ 38.098020] tcp_sendmsg+0x2b/0x40 [ 38.101568] inet_sendmsg+0x15b/0x520 [ 38.105359] sock_sendmsg+0xb7/0x100 [ 38.109058] SyS_sendto+0x1de/0x2f0 [ 38.112667] do_syscall_64+0x19b/0x520 [ 38.116535] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.121725] 0xffffffffffffffff [ 38.124986] [ 38.126712] The buggy address belongs to the object at ffff8881d6fb5400 [ 38.126712] which belongs to the cache skbuff_fclone_cache of size 456 [ 38.140058] The buggy address is located 48 bytes inside of [ 38.140058] 456-byte region [ffff8881d6fb5400, ffff8881d6fb55c8) [ 38.153045] The buggy address belongs to the page: [ 38.158335] page:ffffea00075bed00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 38.168379] flags: 0x4000000000010200(slab|head) [ 38.173123] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 38.180994] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 38.188863] page dumped because: kasan: bad access detected [ 38.194553] [ 38.196165] Memory state around the buggy address: [ 38.201090] ffff8881d6fb5300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 38.208437] ffff8881d6fb5380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 38.215781] >ffff8881d6fb5400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.223125] ^ [ 38.228045] ffff8881d6fb5480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.235554] ffff8881d6fb5500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.242885] ================================================================== [ 38.250225] Disabling lock debugging due to kernel taint [ 38.256140] Kernel panic - not syncing: panic_on_warn set ... [ 38.256140] [ 38.263499] CPU: 0 PID: 1790 Comm: syz-executor280 Tainted: G B 4.14.145+ #0 [ 38.271800] Call Trace: [ 38.274370] dump_stack+0xca/0x134 [ 38.277887] panic+0x1ea/0x3d3 [ 38.281065] ? add_taint.cold+0x16/0x16 [ 38.285017] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.289401] ? ___preempt_schedule+0x16/0x18 [ 38.293799] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.298190] end_report+0x43/0x49 [ 38.301623] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.306023] __kasan_report.cold+0xd/0x41 [ 38.310153] ? kvm_guest_cpu_init+0x220/0x220 [ 38.314645] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.319029] tcp_init_tso_segs+0x19d/0x1f0 [ 38.323238] ? tcp_tso_segs+0x7b/0x1c0 [ 38.327099] tcp_write_xmit+0x15a/0x4730 [ 38.331147] ? memset+0x20/0x40 [ 38.334418] __tcp_push_pending_frames+0xa0/0x230 [ 38.339246] tcp_send_fin+0x154/0xbc0 [ 38.343033] tcp_close+0xc62/0xf40 [ 38.346562] inet_release+0xe9/0x1c0 [ 38.350251] __sock_release+0xd2/0x2c0 [ 38.354112] ? __sock_release+0x2c0/0x2c0 [ 38.358236] sock_close+0x15/0x20 [ 38.361666] __fput+0x25e/0x710 [ 38.364929] task_work_run+0x125/0x1a0 [ 38.368795] do_exit+0x9cb/0x2a20 [ 38.372228] ? mm_update_next_owner+0x610/0x610 [ 38.376876] do_group_exit+0x100/0x2e0 [ 38.380753] SyS_exit_group+0x19/0x20 [ 38.384545] ? do_group_exit+0x2e0/0x2e0 [ 38.388594] do_syscall_64+0x19b/0x520 [ 38.392476] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.397653] RIP: 0033:0x440b38 [ 38.400823] RSP: 002b:00007ffe01a9f9e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 38.408519] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b38 [ 38.417158] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 38.424639] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 38.432094] R10: 0000000020000804 R11: 0000000000000246 R12: 0000000000000001 [ 38.439442] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 38.447916] Kernel Offset: 0x2b400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 38.458849] Rebooting in 86400 seconds..