[....] 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: [ 26.216789] random: sshd: uninitialized urandom read (32 bytes read) [ 26.679936] audit: type=1400 audit(1569026696.805:6): avc: denied { map } for pid=1766 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 [ 26.718091] random: sshd: uninitialized urandom read (32 bytes read) [ 27.228509] random: sshd: uninitialized urandom read (32 bytes read) [ 27.889066] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.174' (ECDSA) to the list of known hosts. [ 33.358391] random: sshd: uninitialized urandom read (32 bytes read) [ 33.451867] audit: type=1400 audit(1569026703.585:7): avc: denied { map } for pid=1784 comm="syz-executor090" path="/root/syz-executor090830993" 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 [ 34.240901] ================================================================== [ 34.248487] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 34.255239] Read of size 2 at addr ffff8881da2c5430 by task syz-executor090/1785 [ 34.262752] [ 34.264363] CPU: 1 PID: 1785 Comm: syz-executor090 Not tainted 4.14.145+ #0 [ 34.271462] Call Trace: [ 34.274038] dump_stack+0xca/0x134 [ 34.277646] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.282035] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.286423] print_address_description+0x60/0x226 [ 34.291260] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.295646] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.300040] __kasan_report.cold+0x1a/0x41 [ 34.304273] ? kvm_guest_cpu_init+0x220/0x220 [ 34.308746] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.313335] tcp_init_tso_segs+0x19d/0x1f0 [ 34.317566] ? tcp_tso_segs+0x7b/0x1c0 [ 34.321455] tcp_write_xmit+0x15a/0x4730 [ 34.325502] ? memset+0x20/0x40 [ 34.328866] __tcp_push_pending_frames+0xa0/0x230 [ 34.333952] tcp_send_fin+0x154/0xbc0 [ 34.337877] tcp_close+0xc62/0xf40 [ 34.341415] inet_release+0xe9/0x1c0 [ 34.345124] __sock_release+0xd2/0x2c0 [ 34.348995] ? __sock_release+0x2c0/0x2c0 [ 34.353141] sock_close+0x15/0x20 [ 34.356577] __fput+0x25e/0x710 [ 34.359842] task_work_run+0x125/0x1a0 [ 34.363730] do_exit+0x9cb/0x2a20 [ 34.367193] ? mm_update_next_owner+0x610/0x610 [ 34.371855] do_group_exit+0x100/0x2e0 [ 34.375727] SyS_exit_group+0x19/0x20 [ 34.379519] ? do_group_exit+0x2e0/0x2e0 [ 34.383560] do_syscall_64+0x19b/0x520 [ 34.387434] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.392602] RIP: 0033:0x440618 [ 34.395858] RSP: 002b:00007ffcb4cd3b38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 34.403567] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 34.410939] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 34.418193] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 34.425447] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 34.432702] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 34.439968] [ 34.441574] Allocated by task 1785: [ 34.445187] __kasan_kmalloc.part.0+0x53/0xc0 [ 34.449671] kmem_cache_alloc+0xee/0x360 [ 34.453727] __alloc_skb+0xea/0x5c0 [ 34.457343] sk_stream_alloc_skb+0xf4/0x8a0 [ 34.461646] tcp_sendmsg_locked+0xf11/0x2f50 [ 34.466050] tcp_sendmsg+0x2b/0x40 [ 34.469574] inet_sendmsg+0x15b/0x520 [ 34.473511] sock_sendmsg+0xb7/0x100 [ 34.477216] SyS_sendto+0x1de/0x2f0 [ 34.480842] do_syscall_64+0x19b/0x520 [ 34.484728] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.489894] 0xffffffffffffffff [ 34.493151] [ 34.494760] Freed by task 1785: [ 34.498033] __kasan_slab_free+0x164/0x210 [ 34.502246] kmem_cache_free+0xd7/0x3b0 [ 34.506201] kfree_skbmem+0x84/0x110 [ 34.510335] tcp_remove_empty_skb+0x264/0x320 [ 34.514829] tcp_sendmsg_locked+0x1c09/0x2f50 [ 34.519338] tcp_sendmsg+0x2b/0x40 [ 34.522861] inet_sendmsg+0x15b/0x520 [ 34.526639] sock_sendmsg+0xb7/0x100 [ 34.530331] SyS_sendto+0x1de/0x2f0 [ 34.534557] do_syscall_64+0x19b/0x520 [ 34.538439] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.543954] 0xffffffffffffffff [ 34.547213] [ 34.548830] The buggy address belongs to the object at ffff8881da2c5400 [ 34.548830] which belongs to the cache skbuff_fclone_cache of size 456 [ 34.562189] The buggy address is located 48 bytes inside of [ 34.562189] 456-byte region [ffff8881da2c5400, ffff8881da2c55c8) [ 34.573959] The buggy address belongs to the page: [ 34.578872] page:ffffea000768b100 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 34.588836] flags: 0x4000000000010200(slab|head) [ 34.593579] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 34.602052] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 34.609927] page dumped because: kasan: bad access detected [ 34.615626] [ 34.617234] Memory state around the buggy address: [ 34.622232] ffff8881da2c5300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 34.629928] ffff8881da2c5380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 34.637480] >ffff8881da2c5400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.645778] ^ [ 34.650701] ffff8881da2c5480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.658054] ffff8881da2c5500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.666280] ================================================================== [ 34.673642] Disabling lock debugging due to kernel taint [ 34.679419] Kernel panic - not syncing: panic_on_warn set ... [ 34.679419] [ 34.686896] CPU: 1 PID: 1785 Comm: syz-executor090 Tainted: G B 4.14.145+ #0 [ 34.695189] Call Trace: [ 34.697763] dump_stack+0xca/0x134 [ 34.701287] panic+0x1ea/0x3d3 [ 34.704460] ? add_taint.cold+0x16/0x16 [ 34.708445] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.712859] ? ___preempt_schedule+0x16/0x18 [ 34.717267] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.721662] end_report+0x43/0x49 [ 34.725200] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.729678] __kasan_report.cold+0xd/0x41 [ 34.733820] ? kvm_guest_cpu_init+0x220/0x220 [ 34.738298] ? tcp_init_tso_segs+0x19d/0x1f0 [ 34.742870] tcp_init_tso_segs+0x19d/0x1f0 [ 34.747431] ? tcp_tso_segs+0x7b/0x1c0 [ 34.754338] tcp_write_xmit+0x15a/0x4730 [ 34.758921] ? memset+0x20/0x40 [ 34.762198] __tcp_push_pending_frames+0xa0/0x230 [ 34.767023] tcp_send_fin+0x154/0xbc0 [ 34.770808] tcp_close+0xc62/0xf40 [ 34.774347] inet_release+0xe9/0x1c0 [ 34.778051] __sock_release+0xd2/0x2c0 [ 34.781928] ? __sock_release+0x2c0/0x2c0 [ 34.786059] sock_close+0x15/0x20 [ 34.789529] __fput+0x25e/0x710 [ 34.793500] task_work_run+0x125/0x1a0 [ 34.797387] do_exit+0x9cb/0x2a20 [ 34.800850] ? mm_update_next_owner+0x610/0x610 [ 34.805643] do_group_exit+0x100/0x2e0 [ 34.809631] SyS_exit_group+0x19/0x20 [ 34.813533] ? do_group_exit+0x2e0/0x2e0 [ 34.817587] do_syscall_64+0x19b/0x520 [ 34.821711] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 34.827145] RIP: 0033:0x440618 [ 34.830316] RSP: 002b:00007ffcb4cd3b38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 34.838011] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 34.845266] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 34.852543] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 34.860170] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 34.868379] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 34.876630] Kernel Offset: 0x35600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 34.887557] Rebooting in 86400 seconds..