[....] 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: [ 48.828703] random: sshd: uninitialized urandom read (32 bytes read) [ 49.167004] audit: type=1400 audit(1569077761.615:6): avc: denied { map } for pid=1782 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 [ 49.213728] random: sshd: uninitialized urandom read (32 bytes read) [ 49.706204] random: sshd: uninitialized urandom read (32 bytes read) [ 49.872389] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts. [ 55.307244] random: sshd: uninitialized urandom read (32 bytes read) [ 55.399845] audit: type=1400 audit(1569077767.845:7): avc: denied { map } for pid=1800 comm="syz-executor407" path="/root/syz-executor407525573" 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 [ 56.211117] ================================================================== [ 56.218551] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 56.226094] Read of size 2 at addr ffff8881d6ee2cb0 by task syz-executor407/1801 [ 56.233599] [ 56.235206] CPU: 1 PID: 1801 Comm: syz-executor407 Not tainted 4.14.145+ #0 [ 56.242362] Call Trace: [ 56.244930] dump_stack+0xca/0x134 [ 56.248447] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.252838] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.257219] print_address_description+0x60/0x226 [ 56.262034] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.266417] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.270798] __kasan_report.cold+0x1a/0x41 [ 56.275011] ? kvm_guest_cpu_init+0x220/0x220 [ 56.279478] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.283863] tcp_init_tso_segs+0x19d/0x1f0 [ 56.288071] ? tcp_tso_segs+0x7b/0x1c0 [ 56.291933] tcp_write_xmit+0x15a/0x4730 [ 56.295974] ? memset+0x20/0x40 [ 56.299235] __tcp_push_pending_frames+0xa0/0x230 [ 56.304051] tcp_send_fin+0x154/0xbc0 [ 56.307863] tcp_close+0xc62/0xf40 [ 56.311400] inet_release+0xe9/0x1c0 [ 56.315088] __sock_release+0xd2/0x2c0 [ 56.318948] ? __sock_release+0x2c0/0x2c0 [ 56.323071] sock_close+0x15/0x20 [ 56.326499] __fput+0x25e/0x710 [ 56.329758] task_work_run+0x125/0x1a0 [ 56.333627] do_exit+0x9cb/0x2a20 [ 56.337061] ? mm_update_next_owner+0x610/0x610 [ 56.341713] do_group_exit+0x100/0x2e0 [ 56.345607] SyS_exit_group+0x19/0x20 [ 56.349401] ? do_group_exit+0x2e0/0x2e0 [ 56.353437] do_syscall_64+0x19b/0x520 [ 56.357304] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 56.362465] RIP: 0033:0x440b38 [ 56.365624] RSP: 002b:00007ffc9181cca8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 56.373303] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b38 [ 56.380581] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 56.387824] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 56.395069] R10: 0000000020000820 R11: 0000000000000246 R12: 0000000000000001 [ 56.402311] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 56.409566] [ 56.411170] Allocated by task 1801: [ 56.414773] __kasan_kmalloc.part.0+0x53/0xc0 [ 56.419327] kmem_cache_alloc+0xee/0x360 [ 56.423362] __alloc_skb+0xea/0x5c0 [ 56.426961] sk_stream_alloc_skb+0xf4/0x8a0 [ 56.431263] tcp_sendmsg_locked+0xf11/0x2f50 [ 56.435647] tcp_sendmsg+0x2b/0x40 [ 56.439168] inet_sendmsg+0x15b/0x520 [ 56.442952] sock_sendmsg+0xb7/0x100 [ 56.446647] SyS_sendto+0x1de/0x2f0 [ 56.450258] do_syscall_64+0x19b/0x520 [ 56.454122] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 56.459282] 0xffffffffffffffff [ 56.462534] [ 56.464145] Freed by task 1801: [ 56.467398] __kasan_slab_free+0x164/0x210 [ 56.471610] kmem_cache_free+0xd7/0x3b0 [ 56.475556] kfree_skbmem+0x84/0x110 [ 56.479242] tcp_remove_empty_skb+0x264/0x320 [ 56.483712] tcp_sendmsg_locked+0x1c09/0x2f50 [ 56.488177] tcp_sendmsg+0x2b/0x40 [ 56.491690] inet_sendmsg+0x15b/0x520 [ 56.495463] sock_sendmsg+0xb7/0x100 [ 56.499164] SyS_sendto+0x1de/0x2f0 [ 56.502766] do_syscall_64+0x19b/0x520 [ 56.506647] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 56.511806] 0xffffffffffffffff [ 56.515056] [ 56.516660] The buggy address belongs to the object at ffff8881d6ee2c80 [ 56.516660] which belongs to the cache skbuff_fclone_cache of size 456 [ 56.529983] The buggy address is located 48 bytes inside of [ 56.529983] 456-byte region [ffff8881d6ee2c80, ffff8881d6ee2e48) [ 56.541750] The buggy address belongs to the page: [ 56.546651] page:ffffea00075bb880 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 56.556628] flags: 0x4000000000010200(slab|head) [ 56.561359] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 56.569217] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 56.577065] page dumped because: kasan: bad access detected [ 56.582749] [ 56.584349] Memory state around the buggy address: [ 56.589251] ffff8881d6ee2b80: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 56.596581] ffff8881d6ee2c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 56.603915] >ffff8881d6ee2c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 56.611255] ^ [ 56.616155] ffff8881d6ee2d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 56.623487] ffff8881d6ee2d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 56.630816] ================================================================== [ 56.638148] Disabling lock debugging due to kernel taint [ 56.643880] Kernel panic - not syncing: panic_on_warn set ... [ 56.643880] [ 56.651243] CPU: 1 PID: 1801 Comm: syz-executor407 Tainted: G B 4.14.145+ #0 [ 56.659531] Call Trace: [ 56.662101] dump_stack+0xca/0x134 [ 56.665618] panic+0x1ea/0x3d3 [ 56.668782] ? add_taint.cold+0x16/0x16 [ 56.672739] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.677134] ? ___preempt_schedule+0x16/0x18 [ 56.681525] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.685905] end_report+0x43/0x49 [ 56.689347] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.693730] __kasan_report.cold+0xd/0x41 [ 56.697849] ? kvm_guest_cpu_init+0x220/0x220 [ 56.702343] ? tcp_init_tso_segs+0x19d/0x1f0 [ 56.706722] tcp_init_tso_segs+0x19d/0x1f0 [ 56.710928] ? tcp_tso_segs+0x7b/0x1c0 [ 56.714790] tcp_write_xmit+0x15a/0x4730 [ 56.718839] ? memset+0x20/0x40 [ 56.722115] __tcp_push_pending_frames+0xa0/0x230 [ 56.726927] tcp_send_fin+0x154/0xbc0 [ 56.730701] tcp_close+0xc62/0xf40 [ 56.734217] inet_release+0xe9/0x1c0 [ 56.737904] __sock_release+0xd2/0x2c0 [ 56.741772] ? __sock_release+0x2c0/0x2c0 [ 56.745985] sock_close+0x15/0x20 [ 56.749412] __fput+0x25e/0x710 [ 56.752669] task_work_run+0x125/0x1a0 [ 56.756532] do_exit+0x9cb/0x2a20 [ 56.759962] ? mm_update_next_owner+0x610/0x610 [ 56.764609] do_group_exit+0x100/0x2e0 [ 56.768469] SyS_exit_group+0x19/0x20 [ 56.772265] ? do_group_exit+0x2e0/0x2e0 [ 56.776299] do_syscall_64+0x19b/0x520 [ 56.780173] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 56.785336] RIP: 0033:0x440b38 [ 56.788501] RSP: 002b:00007ffc9181cca8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 56.796180] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b38 [ 56.803422] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 56.810667] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 56.817912] R10: 0000000020000820 R11: 0000000000000246 R12: 0000000000000001 [ 56.825155] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 56.833037] Kernel Offset: 0x10e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 56.843932] Rebooting in 86400 seconds..