[....] 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: [ 26.214638] random: sshd: uninitialized urandom read (32 bytes read) [ 26.656052] audit: type=1400 audit(1569071531.050:6): 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 [ 26.703539] random: sshd: uninitialized urandom read (32 bytes read) [ 27.238131] random: sshd: uninitialized urandom read (32 bytes read) [ 39.719520] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.15' (ECDSA) to the list of known hosts. [ 45.271712] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 45.360818] audit: type=1400 audit(1569071549.760:7): avc: denied { map } for pid=1789 comm="syz-executor555" path="/root/syz-executor555478123" 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 [ 45.364059] ================================================================== [ 45.394373] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 45.401103] Read of size 2 at addr ffff8881d059ea30 by task syz-executor555/1789 [ 45.408609] [ 45.410221] CPU: 1 PID: 1789 Comm: syz-executor555 Not tainted 4.14.145+ #0 [ 45.417291] Call Trace: [ 45.419860] dump_stack+0xca/0x134 [ 45.423394] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.427781] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.432168] print_address_description+0x60/0x226 [ 45.437071] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.441455] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.445838] __kasan_report.cold+0x1a/0x41 [ 45.450057] ? kvm_guest_cpu_init+0x220/0x220 [ 45.454529] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.459002] tcp_init_tso_segs+0x19d/0x1f0 [ 45.463252] ? tcp_tso_segs+0x7b/0x1c0 [ 45.467115] tcp_write_xmit+0x15a/0x4730 [ 45.471159] ? memset+0x20/0x40 [ 45.474434] __tcp_push_pending_frames+0xa0/0x230 [ 45.479294] tcp_send_fin+0x154/0xbc0 [ 45.483078] tcp_close+0xc62/0xf40 [ 45.486600] inet_release+0xe9/0x1c0 [ 45.490292] __sock_release+0xd2/0x2c0 [ 45.494155] ? __sock_release+0x2c0/0x2c0 [ 45.498275] sock_close+0x15/0x20 [ 45.501705] __fput+0x25e/0x710 [ 45.504967] task_work_run+0x125/0x1a0 [ 45.508836] do_exit+0x9cb/0x2a20 [ 45.512274] ? mm_update_next_owner+0x610/0x610 [ 45.516928] do_group_exit+0x100/0x2e0 [ 45.520795] SyS_exit_group+0x19/0x20 [ 45.524569] ? do_group_exit+0x2e0/0x2e0 [ 45.528604] do_syscall_64+0x19b/0x520 [ 45.532474] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 45.537641] RIP: 0033:0x43ee08 [ 45.540807] RSP: 002b:00007ffc754bda68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 45.548501] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee08 [ 45.555745] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 45.562992] RBP: 00000000004be608 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 45.570237] R10: 0900000020000000 R11: 0000000000000246 R12: 0000000000000001 [ 45.577494] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 45.584751] [ 45.586357] Allocated by task 1789: [ 45.589972] __kasan_kmalloc.part.0+0x53/0xc0 [ 45.594440] kmem_cache_alloc+0xee/0x360 [ 45.598475] __alloc_skb+0xea/0x5c0 [ 45.602079] sk_stream_alloc_skb+0xf4/0x8a0 [ 45.606403] tcp_sendmsg_locked+0xf11/0x2f50 [ 45.610786] tcp_sendmsg+0x2b/0x40 [ 45.614303] inet_sendmsg+0x15b/0x520 [ 45.618087] sock_sendmsg+0xb7/0x100 [ 45.621780] SyS_sendto+0x1de/0x2f0 [ 45.625447] do_syscall_64+0x19b/0x520 [ 45.629312] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 45.634477] 0xffffffffffffffff [ 45.637729] [ 45.639330] Freed by task 1789: [ 45.642588] __kasan_slab_free+0x164/0x210 [ 45.646797] kmem_cache_free+0xd7/0x3b0 [ 45.650748] kfree_skbmem+0x84/0x110 [ 45.654450] tcp_remove_empty_skb+0x264/0x320 [ 45.658941] tcp_sendmsg_locked+0x1c09/0x2f50 [ 45.663409] tcp_sendmsg+0x2b/0x40 [ 45.666932] inet_sendmsg+0x15b/0x520 [ 45.670706] sock_sendmsg+0xb7/0x100 [ 45.674393] SyS_sendto+0x1de/0x2f0 [ 45.677995] do_syscall_64+0x19b/0x520 [ 45.681861] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 45.687040] 0xffffffffffffffff [ 45.690293] [ 45.691904] The buggy address belongs to the object at ffff8881d059ea00 [ 45.691904] which belongs to the cache skbuff_fclone_cache of size 456 [ 45.705232] The buggy address is located 48 bytes inside of [ 45.705232] 456-byte region [ffff8881d059ea00, ffff8881d059ebc8) [ 45.717001] The buggy address belongs to the page: [ 45.721905] page:ffffea0007416780 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 45.731859] flags: 0x4000000000010200(slab|head) [ 45.736590] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 45.744447] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 45.752298] page dumped because: kasan: bad access detected [ 45.757982] [ 45.759594] Memory state around the buggy address: [ 45.764507] ffff8881d059e900: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 45.771895] ffff8881d059e980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 45.779289] >ffff8881d059ea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.786634] ^ [ 45.791539] ffff8881d059ea80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.798884] ffff8881d059eb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.806225] ================================================================== [ 45.813615] Disabling lock debugging due to kernel taint [ 45.819365] Kernel panic - not syncing: panic_on_warn set ... [ 45.819365] [ 45.826718] CPU: 1 PID: 1789 Comm: syz-executor555 Tainted: G B 4.14.145+ #0 [ 45.835004] Call Trace: [ 45.837572] dump_stack+0xca/0x134 [ 45.841090] panic+0x1ea/0x3d3 [ 45.844298] ? add_taint.cold+0x16/0x16 [ 45.848250] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.852633] ? ___preempt_schedule+0x16/0x18 [ 45.857190] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.861577] end_report+0x43/0x49 [ 45.865003] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.870167] __kasan_report.cold+0xd/0x41 [ 45.874337] ? kvm_guest_cpu_init+0x220/0x220 [ 45.878816] ? tcp_init_tso_segs+0x19d/0x1f0 [ 45.883199] tcp_init_tso_segs+0x19d/0x1f0 [ 45.887406] ? tcp_tso_segs+0x7b/0x1c0 [ 45.891267] tcp_write_xmit+0x15a/0x4730 [ 45.895306] ? memset+0x20/0x40 [ 45.898562] __tcp_push_pending_frames+0xa0/0x230 [ 45.903378] tcp_send_fin+0x154/0xbc0 [ 45.907158] tcp_close+0xc62/0xf40 [ 45.910676] inet_release+0xe9/0x1c0 [ 45.914370] __sock_release+0xd2/0x2c0 [ 45.918232] ? __sock_release+0x2c0/0x2c0 [ 45.922353] sock_close+0x15/0x20 [ 45.925780] __fput+0x25e/0x710 [ 45.929041] task_work_run+0x125/0x1a0 [ 45.932909] do_exit+0x9cb/0x2a20 [ 45.936350] ? mm_update_next_owner+0x610/0x610 [ 45.941001] do_group_exit+0x100/0x2e0 [ 45.944867] SyS_exit_group+0x19/0x20 [ 45.948644] ? do_group_exit+0x2e0/0x2e0 [ 45.952680] do_syscall_64+0x19b/0x520 [ 45.956545] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 45.961721] RIP: 0033:0x43ee08 [ 45.964888] RSP: 002b:00007ffc754bda68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 45.972570] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee08 [ 45.979813] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 45.987058] RBP: 00000000004be608 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 45.994300] R10: 0900000020000000 R11: 0000000000000246 R12: 0000000000000001 [ 46.001543] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 46.009611] Kernel Offset: 0x13a00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 46.020511] Rebooting in 86400 seconds..