[....] 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: [ 34.395461] random: sshd: uninitialized urandom read (32 bytes read) [ 34.762543] audit: type=1400 audit(1569019947.062:6): avc: denied { map } for pid=1768 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 [ 34.806894] random: sshd: uninitialized urandom read (32 bytes read) [ 35.337401] random: sshd: uninitialized urandom read (32 bytes read) [ 57.073123] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.226' (ECDSA) to the list of known hosts. [ 62.525651] random: sshd: uninitialized urandom read (32 bytes read) [ 62.621591] audit: type=1400 audit(1569019974.922:7): avc: denied { map } for pid=1798 comm="syz-executor322" path="/root/syz-executor322461589" 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 [ 63.400678] ================================================================== [ 63.408208] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 63.414989] Read of size 2 at addr ffff8881c518dbb0 by task syz-executor322/1799 [ 63.422545] [ 63.424174] CPU: 0 PID: 1799 Comm: syz-executor322 Not tainted 4.14.145+ #0 [ 63.431249] Call Trace: [ 63.433840] dump_stack+0xca/0x134 [ 63.437363] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.441760] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.446160] print_address_description+0x60/0x226 [ 63.451069] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.455458] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.459844] __kasan_report.cold+0x1a/0x41 [ 63.464063] ? kvm_guest_cpu_init+0x220/0x220 [ 63.468554] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.472949] tcp_init_tso_segs+0x19d/0x1f0 [ 63.477163] ? tcp_tso_segs+0x7b/0x1c0 [ 63.481031] tcp_write_xmit+0x15a/0x4730 [ 63.485080] ? memset+0x20/0x40 [ 63.488344] __tcp_push_pending_frames+0xa0/0x230 [ 63.493166] tcp_send_fin+0x154/0xbc0 [ 63.496950] tcp_close+0xc62/0xf40 [ 63.500478] inet_release+0xe9/0x1c0 [ 63.504186] __sock_release+0xd2/0x2c0 [ 63.508067] ? __sock_release+0x2c0/0x2c0 [ 63.512190] sock_close+0x15/0x20 [ 63.515640] __fput+0x25e/0x710 [ 63.518903] task_work_run+0x125/0x1a0 [ 63.522775] do_exit+0x9cb/0x2a20 [ 63.526213] ? mm_update_next_owner+0x610/0x610 [ 63.530886] do_group_exit+0x100/0x2e0 [ 63.534755] SyS_exit_group+0x19/0x20 [ 63.538537] ? do_group_exit+0x2e0/0x2e0 [ 63.542578] do_syscall_64+0x19b/0x520 [ 63.546452] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.551625] RIP: 0033:0x440618 [ 63.554809] RSP: 002b:00007ffecdab7a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 63.562498] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 63.569745] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 63.576994] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 63.584431] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 63.591680] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 63.598947] [ 63.600559] Allocated by task 1799: [ 63.604177] __kasan_kmalloc.part.0+0x53/0xc0 [ 63.608650] kmem_cache_alloc+0xee/0x360 [ 63.612703] __alloc_skb+0xea/0x5c0 [ 63.616309] sk_stream_alloc_skb+0xf4/0x8a0 [ 63.620609] tcp_sendmsg_locked+0xf11/0x2f50 [ 63.624993] tcp_sendmsg+0x2b/0x40 [ 63.628529] inet_sendmsg+0x15b/0x520 [ 63.632307] sock_sendmsg+0xb7/0x100 [ 63.636009] SyS_sendto+0x1de/0x2f0 [ 63.639613] do_syscall_64+0x19b/0x520 [ 63.643494] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.648661] 0xffffffffffffffff [ 63.651929] [ 63.653546] Freed by task 1799: [ 63.656816] __kasan_slab_free+0x164/0x210 [ 63.661139] kmem_cache_free+0xd7/0x3b0 [ 63.665102] kfree_skbmem+0x84/0x110 [ 63.668797] tcp_remove_empty_skb+0x264/0x320 [ 63.673270] tcp_sendmsg_locked+0x1c09/0x2f50 [ 63.677740] tcp_sendmsg+0x2b/0x40 [ 63.681271] inet_sendmsg+0x15b/0x520 [ 63.685049] sock_sendmsg+0xb7/0x100 [ 63.688741] SyS_sendto+0x1de/0x2f0 [ 63.692348] do_syscall_64+0x19b/0x520 [ 63.696214] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.701380] 0xffffffffffffffff [ 63.704633] [ 63.706257] The buggy address belongs to the object at ffff8881c518db80 [ 63.706257] which belongs to the cache skbuff_fclone_cache of size 456 [ 63.719599] The buggy address is located 48 bytes inside of [ 63.719599] 456-byte region [ffff8881c518db80, ffff8881c518dd48) [ 63.731378] The buggy address belongs to the page: [ 63.736287] page:ffffea0007146300 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 63.746311] flags: 0x4000000000010200(slab|head) [ 63.751058] raw: 4000000000010200 0000000000000000 0000000000000000 00000001000c000c [ 63.758934] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 63.766806] page dumped because: kasan: bad access detected [ 63.772491] [ 63.774149] Memory state around the buggy address: [ 63.779060] ffff8881c518da80: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 63.786400] ffff8881c518db00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 63.793754] >ffff8881c518db80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.801102] ^ [ 63.806008] ffff8881c518dc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.813352] ffff8881c518dc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 63.820688] ================================================================== [ 63.828111] Disabling lock debugging due to kernel taint [ 63.834167] Kernel panic - not syncing: panic_on_warn set ... [ 63.834167] [ 63.841538] CPU: 0 PID: 1799 Comm: syz-executor322 Tainted: G B 4.14.145+ #0 [ 63.849827] Call Trace: [ 63.852402] dump_stack+0xca/0x134 [ 63.855921] panic+0x1ea/0x3d3 [ 63.859116] ? add_taint.cold+0x16/0x16 [ 63.863068] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.867452] ? ___preempt_schedule+0x16/0x18 [ 63.871851] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.876236] end_report+0x43/0x49 [ 63.879665] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.884049] __kasan_report.cold+0xd/0x41 [ 63.888187] ? kvm_guest_cpu_init+0x220/0x220 [ 63.892656] ? tcp_init_tso_segs+0x19d/0x1f0 [ 63.897058] tcp_init_tso_segs+0x19d/0x1f0 [ 63.901269] ? tcp_tso_segs+0x7b/0x1c0 [ 63.905134] tcp_write_xmit+0x15a/0x4730 [ 63.909174] ? memset+0x20/0x40 [ 63.912434] __tcp_push_pending_frames+0xa0/0x230 [ 63.917271] tcp_send_fin+0x154/0xbc0 [ 63.921054] tcp_close+0xc62/0xf40 [ 63.924609] inet_release+0xe9/0x1c0 [ 63.928312] __sock_release+0xd2/0x2c0 [ 63.932177] ? __sock_release+0x2c0/0x2c0 [ 63.936310] sock_close+0x15/0x20 [ 63.939742] __fput+0x25e/0x710 [ 63.943026] task_work_run+0x125/0x1a0 [ 63.946894] do_exit+0x9cb/0x2a20 [ 63.950329] ? mm_update_next_owner+0x610/0x610 [ 63.954990] do_group_exit+0x100/0x2e0 [ 63.958862] SyS_exit_group+0x19/0x20 [ 63.962647] ? do_group_exit+0x2e0/0x2e0 [ 63.966682] do_syscall_64+0x19b/0x520 [ 63.970562] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 63.975730] RIP: 0033:0x440618 [ 63.978907] RSP: 002b:00007ffecdab7a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 63.986591] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 63.993839] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 64.001085] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 64.008332] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 64.015667] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 64.023687] Kernel Offset: 0xc00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 64.035052] Rebooting in 86400 seconds..