[....] 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: [ 26.435772] random: sshd: uninitialized urandom read (32 bytes read) [ 26.777097] audit: type=1400 audit(1569083783.105:6): avc: denied { map } for pid=1765 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 [ 26.821358] random: sshd: uninitialized urandom read (32 bytes read) [ 27.326848] random: sshd: uninitialized urandom read (32 bytes read) [ 41.127602] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.54' (ECDSA) to the list of known hosts. [ 46.592598] random: sshd: uninitialized urandom read (32 bytes read) [ 46.680877] audit: type=1400 audit(1569083803.015:7): avc: denied { map } for pid=1789 comm="syz-executor893" path="/root/syz-executor893757798" 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 [ 47.441379] ================================================================== [ 47.448941] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 47.455677] Read of size 2 at addr ffff8881d0db96b0 by task syz-executor893/1790 [ 47.463187] [ 47.464799] CPU: 0 PID: 1790 Comm: syz-executor893 Not tainted 4.14.145+ #0 [ 47.471871] Call Trace: [ 47.474449] dump_stack+0xca/0x134 [ 47.477971] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.482358] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.486746] print_address_description+0x60/0x226 [ 47.491568] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.495966] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.500367] __kasan_report.cold+0x1a/0x41 [ 47.504586] ? kvm_guest_cpu_init+0x220/0x220 [ 47.509060] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.513488] tcp_init_tso_segs+0x19d/0x1f0 [ 47.517697] ? tcp_tso_segs+0x7b/0x1c0 [ 47.521582] tcp_write_xmit+0x15a/0x4730 [ 47.525630] ? memset+0x20/0x40 [ 47.528908] __tcp_push_pending_frames+0xa0/0x230 [ 47.533731] tcp_send_fin+0x154/0xbc0 [ 47.537513] tcp_close+0xc62/0xf40 [ 47.541037] inet_release+0xe9/0x1c0 [ 47.544731] __sock_release+0xd2/0x2c0 [ 47.548599] ? __sock_release+0x2c0/0x2c0 [ 47.552720] sock_close+0x15/0x20 [ 47.556149] __fput+0x25e/0x710 [ 47.559434] task_work_run+0x125/0x1a0 [ 47.563325] do_exit+0x9cb/0x2a20 [ 47.566761] ? mm_update_next_owner+0x610/0x610 [ 47.571429] do_group_exit+0x100/0x2e0 [ 47.575296] SyS_exit_group+0x19/0x20 [ 47.579072] ? do_group_exit+0x2e0/0x2e0 [ 47.583107] do_syscall_64+0x19b/0x520 [ 47.586986] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.592153] RIP: 0033:0x440618 [ 47.595323] RSP: 002b:00007fff09efa2e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 47.603006] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 47.610251] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 47.617503] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 47.624762] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 47.632021] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 47.639279] [ 47.640882] Allocated by task 1790: [ 47.644491] __kasan_kmalloc.part.0+0x53/0xc0 [ 47.648963] kmem_cache_alloc+0xee/0x360 [ 47.653000] __alloc_skb+0xea/0x5c0 [ 47.656606] sk_stream_alloc_skb+0xf4/0x8a0 [ 47.660902] tcp_sendmsg_locked+0xf11/0x2f50 [ 47.665287] tcp_sendmsg+0x2b/0x40 [ 47.668804] inet_sendmsg+0x15b/0x520 [ 47.672595] sock_sendmsg+0xb7/0x100 [ 47.676284] SyS_sendto+0x1de/0x2f0 [ 47.679903] do_syscall_64+0x19b/0x520 [ 47.683770] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.688932] 0xffffffffffffffff [ 47.692185] [ 47.693789] Freed by task 1790: [ 47.697066] __kasan_slab_free+0x164/0x210 [ 47.701278] kmem_cache_free+0xd7/0x3b0 [ 47.705315] kfree_skbmem+0x84/0x110 [ 47.709006] tcp_remove_empty_skb+0x264/0x320 [ 47.713490] tcp_sendmsg_locked+0x1c09/0x2f50 [ 47.717961] tcp_sendmsg+0x2b/0x40 [ 47.721585] inet_sendmsg+0x15b/0x520 [ 47.725379] sock_sendmsg+0xb7/0x100 [ 47.729067] SyS_sendto+0x1de/0x2f0 [ 47.732669] do_syscall_64+0x19b/0x520 [ 47.736545] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.741708] 0xffffffffffffffff [ 47.744957] [ 47.746562] The buggy address belongs to the object at ffff8881d0db9680 [ 47.746562] which belongs to the cache skbuff_fclone_cache of size 456 [ 47.759903] The buggy address is located 48 bytes inside of [ 47.759903] 456-byte region [ffff8881d0db9680, ffff8881d0db9848) [ 47.771664] The buggy address belongs to the page: [ 47.776570] page:ffffea0007436e00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 47.786688] flags: 0x4000000000010200(slab|head) [ 47.791421] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 47.799275] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 47.807129] page dumped because: kasan: bad access detected [ 47.812817] [ 47.814420] Memory state around the buggy address: [ 47.819323] ffff8881d0db9580: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 47.826661] ffff8881d0db9600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 47.834011] >ffff8881d0db9680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.841412] ^ [ 47.846344] ffff8881d0db9700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.853685] ffff8881d0db9780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.861267] ================================================================== [ 47.868603] Disabling lock debugging due to kernel taint [ 47.874383] Kernel panic - not syncing: panic_on_warn set ... [ 47.874383] [ 47.881743] CPU: 0 PID: 1790 Comm: syz-executor893 Tainted: G B 4.14.145+ #0 [ 47.890034] Call Trace: [ 47.892619] dump_stack+0xca/0x134 [ 47.896138] panic+0x1ea/0x3d3 [ 47.899319] ? add_taint.cold+0x16/0x16 [ 47.903272] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.907658] ? ___preempt_schedule+0x16/0x18 [ 47.912059] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.916446] end_report+0x43/0x49 [ 47.919874] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.924273] __kasan_report.cold+0xd/0x41 [ 47.928402] ? kvm_guest_cpu_init+0x220/0x220 [ 47.932875] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.937258] tcp_init_tso_segs+0x19d/0x1f0 [ 47.941470] ? tcp_tso_segs+0x7b/0x1c0 [ 47.945332] tcp_write_xmit+0x15a/0x4730 [ 47.949389] ? memset+0x20/0x40 [ 47.952735] __tcp_push_pending_frames+0xa0/0x230 [ 47.957569] tcp_send_fin+0x154/0xbc0 [ 47.961358] tcp_close+0xc62/0xf40 [ 47.964888] inet_release+0xe9/0x1c0 [ 47.968589] __sock_release+0xd2/0x2c0 [ 47.972458] ? __sock_release+0x2c0/0x2c0 [ 47.976749] sock_close+0x15/0x20 [ 47.980211] __fput+0x25e/0x710 [ 47.983473] task_work_run+0x125/0x1a0 [ 47.987340] do_exit+0x9cb/0x2a20 [ 47.990775] ? mm_update_next_owner+0x610/0x610 [ 47.995425] do_group_exit+0x100/0x2e0 [ 47.999289] SyS_exit_group+0x19/0x20 [ 48.003063] ? do_group_exit+0x2e0/0x2e0 [ 48.007192] do_syscall_64+0x19b/0x520 [ 48.011059] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.016223] RIP: 0033:0x440618 [ 48.019388] RSP: 002b:00007fff09efa2e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.027070] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 48.034317] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 48.041563] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.048806] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 48.056051] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 48.063356] Kernel Offset: 0x39a00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 48.074250] Rebooting in 86400 seconds..