[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.067171] random: sshd: uninitialized urandom read (32 bytes read) [ 31.424848] audit: type=1400 audit(1569034226.793:6): avc: denied { map } for pid=1774 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 [ 31.468620] random: sshd: uninitialized urandom read (32 bytes read) [ 31.972951] random: sshd: uninitialized urandom read (32 bytes read) [ 32.134486] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.54' (ECDSA) to the list of known hosts. [ 37.651593] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 37.743823] audit: type=1400 audit(1569034233.113:7): avc: denied { map } for pid=1786 comm="syz-executor083" path="/root/syz-executor083102962" 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 [ 37.747805] ================================================================== [ 37.778872] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 37.785895] Read of size 2 at addr ffff8881d19ad430 by task syz-executor083/1786 [ 37.793733] [ 37.795356] CPU: 0 PID: 1786 Comm: syz-executor083 Not tainted 4.14.145+ #0 [ 37.802525] Call Trace: [ 37.805109] dump_stack+0xca/0x134 [ 37.809001] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.814047] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.818454] print_address_description+0x60/0x226 [ 37.823292] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.827689] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.832285] __kasan_report.cold+0x1a/0x41 [ 37.836517] ? kvm_guest_cpu_init+0x220/0x220 [ 37.841120] ? tcp_init_tso_segs+0x19d/0x1f0 [ 37.845645] tcp_init_tso_segs+0x19d/0x1f0 [ 37.850461] ? tcp_tso_segs+0x7b/0x1c0 [ 37.854359] tcp_write_xmit+0x15a/0x4730 [ 37.858413] ? ip6_mtu+0x206/0x330 [ 37.861950] ? lock_downgrade+0x5d0/0x5d0 [ 37.866172] ? lock_acquire+0x12b/0x360 [ 37.870168] __tcp_push_pending_frames+0xa0/0x230 [ 37.875096] tcp_send_fin+0x154/0xbc0 [ 37.879019] tcp_close+0xc62/0xf40 [ 37.882552] ? lock_acquire+0x12b/0x360 [ 37.886848] ? __sock_release+0x86/0x2c0 [ 37.890910] inet_release+0xe9/0x1c0 [ 37.894624] inet6_release+0x4c/0x70 [ 37.898507] __sock_release+0xd2/0x2c0 [ 37.902411] ? __sock_release+0x2c0/0x2c0 [ 37.906833] sock_close+0x15/0x20 [ 37.910372] __fput+0x25e/0x710 [ 37.913671] task_work_run+0x125/0x1a0 [ 37.917718] do_exit+0x9cb/0x2a20 [ 37.921171] ? mm_update_next_owner+0x610/0x610 [ 37.926051] ? SyS_socket+0x143/0x1e0 [ 37.930134] do_group_exit+0x100/0x2e0 [ 37.934146] SyS_exit_group+0x19/0x20 [ 37.937967] ? do_group_exit+0x2e0/0x2e0 [ 37.942077] do_syscall_64+0x19b/0x520 [ 37.946082] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 37.951553] RIP: 0033:0x43ee88 [ 37.954742] RSP: 002b:00007ffc519fa178 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 37.962556] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 37.969838] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 37.977305] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 37.984568] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 37.993035] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 38.000770] [ 38.002384] Allocated by task 1786: [ 38.006026] __kasan_kmalloc.part.0+0x53/0xc0 [ 38.010597] kmem_cache_alloc+0xee/0x360 [ 38.014909] __alloc_skb+0xea/0x5c0 [ 38.018798] sk_stream_alloc_skb+0xf4/0x8a0 [ 38.023215] tcp_sendmsg_locked+0xf11/0x2f50 [ 38.028066] tcp_sendmsg+0x2b/0x40 [ 38.031722] inet_sendmsg+0x15b/0x520 [ 38.035514] sock_sendmsg+0xb7/0x100 [ 38.039608] SyS_sendto+0x1de/0x2f0 [ 38.043480] do_syscall_64+0x19b/0x520 [ 38.047358] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.053195] 0xffffffffffffffff [ 38.056464] [ 38.058133] Freed by task 1786: [ 38.061404] __kasan_slab_free+0x164/0x210 [ 38.065641] kmem_cache_free+0xd7/0x3b0 [ 38.069607] kfree_skbmem+0x84/0x110 [ 38.073309] tcp_remove_empty_skb+0x264/0x320 [ 38.077791] tcp_sendmsg_locked+0x1c09/0x2f50 [ 38.082276] tcp_sendmsg+0x2b/0x40 [ 38.085805] inet_sendmsg+0x15b/0x520 [ 38.089593] sock_sendmsg+0xb7/0x100 [ 38.093516] SyS_sendto+0x1de/0x2f0 [ 38.097137] do_syscall_64+0x19b/0x520 [ 38.101317] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.106497] 0xffffffffffffffff [ 38.109758] [ 38.111379] The buggy address belongs to the object at ffff8881d19ad400 [ 38.111379] which belongs to the cache skbuff_fclone_cache of size 456 [ 38.124740] The buggy address is located 48 bytes inside of [ 38.124740] 456-byte region [ffff8881d19ad400, ffff8881d19ad5c8) [ 38.136698] The buggy address belongs to the page: [ 38.141622] page:ffffea0007466b00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 38.151966] flags: 0x4000000000010200(slab|head) [ 38.156873] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 38.164921] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 38.172789] page dumped because: kasan: bad access detected [ 38.178899] [ 38.180697] Memory state around the buggy address: [ 38.186171] ffff8881d19ad300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 38.193522] ffff8881d19ad380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 38.201144] >ffff8881d19ad400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.208670] ^ [ 38.213642] ffff8881d19ad480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.221236] ffff8881d19ad500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.228688] ================================================================== [ 38.236050] Disabling lock debugging due to kernel taint [ 38.242176] Kernel panic - not syncing: panic_on_warn set ... [ 38.242176] [ 38.249889] CPU: 0 PID: 1786 Comm: syz-executor083 Tainted: G B 4.14.145+ #0 [ 38.258378] Call Trace: [ 38.261004] dump_stack+0xca/0x134 [ 38.264535] panic+0x1ea/0x3d3 [ 38.267730] ? add_taint.cold+0x16/0x16 [ 38.272049] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.276713] ? ___preempt_schedule+0x16/0x18 [ 38.281215] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.285612] end_report+0x43/0x49 [ 38.289185] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.293671] __kasan_report.cold+0xd/0x41 [ 38.297810] ? kvm_guest_cpu_init+0x220/0x220 [ 38.302290] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.306683] tcp_init_tso_segs+0x19d/0x1f0 [ 38.310996] ? tcp_tso_segs+0x7b/0x1c0 [ 38.314988] tcp_write_xmit+0x15a/0x4730 [ 38.319208] ? ip6_mtu+0x206/0x330 [ 38.322863] ? lock_downgrade+0x5d0/0x5d0 [ 38.327330] ? lock_acquire+0x12b/0x360 [ 38.331435] __tcp_push_pending_frames+0xa0/0x230 [ 38.336268] tcp_send_fin+0x154/0xbc0 [ 38.340063] tcp_close+0xc62/0xf40 [ 38.343598] ? lock_acquire+0x12b/0x360 [ 38.347683] ? __sock_release+0x86/0x2c0 [ 38.351817] inet_release+0xe9/0x1c0 [ 38.355608] inet6_release+0x4c/0x70 [ 38.359397] __sock_release+0xd2/0x2c0 [ 38.363321] ? __sock_release+0x2c0/0x2c0 [ 38.367496] sock_close+0x15/0x20 [ 38.371140] __fput+0x25e/0x710 [ 38.374587] task_work_run+0x125/0x1a0 [ 38.378478] do_exit+0x9cb/0x2a20 [ 38.382109] ? mm_update_next_owner+0x610/0x610 [ 38.387035] ? SyS_socket+0x143/0x1e0 [ 38.390833] do_group_exit+0x100/0x2e0 [ 38.394716] SyS_exit_group+0x19/0x20 [ 38.398654] ? do_group_exit+0x2e0/0x2e0 [ 38.402971] do_syscall_64+0x19b/0x520 [ 38.406856] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.412155] RIP: 0033:0x43ee88 [ 38.415336] RSP: 002b:00007ffc519fa178 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 38.423567] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 38.431006] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 38.439136] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 38.446910] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 38.454438] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 38.463170] Kernel Offset: 0x5400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 38.474770] Rebooting in 86400 seconds..