[ 10.850097] random: sshd: uninitialized urandom read (32 bytes read) [....] 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: [ 16.069775] random: sshd: uninitialized urandom read (32 bytes read) [ 16.260712] audit: type=1400 audit(1569055063.386:6): avc: denied { map } for pid=1758 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 [ 16.299101] random: sshd: uninitialized urandom read (32 bytes read) [ 16.821419] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.35' (ECDSA) to the list of known hosts. [ 22.394332] urandom_read: 1 callbacks suppressed [ 22.394337] random: sshd: uninitialized urandom read (32 bytes read) [ 22.492477] audit: type=1400 audit(1569055069.616:7): avc: denied { map } for pid=1776 comm="syz-executor944" path="/root/syz-executor944906143" 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 [ 23.351037] ================================================================== [ 23.358492] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 23.365241] Read of size 2 at addr ffff8881c5415930 by task syz-executor944/1777 [ 23.372867] [ 23.374483] CPU: 0 PID: 1777 Comm: syz-executor944 Not tainted 4.14.145+ #0 [ 23.381573] Call Trace: [ 23.384168] dump_stack+0xca/0x134 [ 23.387720] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.392111] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.396647] print_address_description+0x60/0x226 [ 23.401477] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.405916] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.410379] __kasan_report.cold+0x1a/0x41 [ 23.414601] ? kvm_guest_cpu_init+0x220/0x220 [ 23.419098] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.423518] tcp_init_tso_segs+0x19d/0x1f0 [ 23.427747] ? tcp_tso_segs+0x7b/0x1c0 [ 23.431652] tcp_write_xmit+0x15a/0x4730 [ 23.435703] ? memset+0x20/0x40 [ 23.438973] __tcp_push_pending_frames+0xa0/0x230 [ 23.443801] tcp_send_fin+0x154/0xbc0 [ 23.447589] tcp_close+0xc62/0xf40 [ 23.451114] inet_release+0xe9/0x1c0 [ 23.454821] __sock_release+0xd2/0x2c0 [ 23.458804] ? __sock_release+0x2c0/0x2c0 [ 23.462941] sock_close+0x15/0x20 [ 23.466376] __fput+0x25e/0x710 [ 23.469654] task_work_run+0x125/0x1a0 [ 23.473651] do_exit+0x9cb/0x2a20 [ 23.477100] ? mm_update_next_owner+0x610/0x610 [ 23.481770] do_group_exit+0x100/0x2e0 [ 23.485735] SyS_exit_group+0x19/0x20 [ 23.489520] ? do_group_exit+0x2e0/0x2e0 [ 23.493577] do_syscall_64+0x19b/0x520 [ 23.497455] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 23.502627] RIP: 0033:0x440b48 [ 23.505811] RSP: 002b:00007ffeb4c05b18 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 23.513502] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b48 [ 23.520772] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 23.528024] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 23.535291] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 23.542553] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 23.549820] [ 23.551431] Allocated by task 1777: [ 23.555044] __kasan_kmalloc.part.0+0x53/0xc0 [ 23.559901] kmem_cache_alloc+0xee/0x360 [ 23.563950] __alloc_skb+0xea/0x5c0 [ 23.567694] sk_stream_alloc_skb+0xf4/0x8a0 [ 23.572028] tcp_sendmsg_locked+0xf11/0x2f50 [ 23.576437] tcp_sendmsg+0x2b/0x40 [ 23.580039] inet_sendmsg+0x15b/0x520 [ 23.583819] sock_sendmsg+0xb7/0x100 [ 23.587511] SyS_sendto+0x1de/0x2f0 [ 23.591291] do_syscall_64+0x19b/0x520 [ 23.595160] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 23.600342] 0xffffffffffffffff [ 23.603599] [ 23.605203] Freed by task 1777: [ 23.608486] __kasan_slab_free+0x164/0x210 [ 23.612710] kmem_cache_free+0xd7/0x3b0 [ 23.616674] kfree_skbmem+0x84/0x110 [ 23.620373] tcp_remove_empty_skb+0x264/0x320 [ 23.624864] tcp_sendmsg_locked+0x1c09/0x2f50 [ 23.629353] tcp_sendmsg+0x2b/0x40 [ 23.632875] inet_sendmsg+0x15b/0x520 [ 23.636665] sock_sendmsg+0xb7/0x100 [ 23.640360] SyS_sendto+0x1de/0x2f0 [ 23.643974] do_syscall_64+0x19b/0x520 [ 23.647944] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 23.653125] 0xffffffffffffffff [ 23.656752] [ 23.658357] The buggy address belongs to the object at ffff8881c5415900 [ 23.658357] which belongs to the cache skbuff_fclone_cache of size 456 [ 23.672297] The buggy address is located 48 bytes inside of [ 23.672297] 456-byte region [ffff8881c5415900, ffff8881c5415ac8) [ 23.684067] The buggy address belongs to the page: [ 23.688978] page:ffffea0007150500 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 23.698935] flags: 0x4000000000010200(slab|head) [ 23.703680] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 23.711555] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 23.719415] page dumped because: kasan: bad access detected [ 23.725311] [ 23.726920] Memory state around the buggy address: [ 23.731828] ffff8881c5415800: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 23.739182] ffff8881c5415880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 23.746530] >ffff8881c5415900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 23.753865] ^ [ 23.758796] ffff8881c5415980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 23.766135] ffff8881c5415a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 23.773472] ================================================================== [ 23.781084] Disabling lock debugging due to kernel taint [ 23.787363] Kernel panic - not syncing: panic_on_warn set ... [ 23.787363] [ 23.794844] CPU: 0 PID: 1777 Comm: syz-executor944 Tainted: G B 4.14.145+ #0 [ 23.803145] Call Trace: [ 23.805714] dump_stack+0xca/0x134 [ 23.809241] panic+0x1ea/0x3d3 [ 23.812418] ? add_taint.cold+0x16/0x16 [ 23.816381] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.820782] ? ___preempt_schedule+0x16/0x18 [ 23.825182] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.829580] end_report+0x43/0x49 [ 23.833029] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.837417] __kasan_report.cold+0xd/0x41 [ 23.841549] ? kvm_guest_cpu_init+0x220/0x220 [ 23.846127] ? tcp_init_tso_segs+0x19d/0x1f0 [ 23.850518] tcp_init_tso_segs+0x19d/0x1f0 [ 23.854816] ? tcp_tso_segs+0x7b/0x1c0 [ 23.858684] tcp_write_xmit+0x15a/0x4730 [ 23.862729] ? memset+0x20/0x40 [ 23.866004] __tcp_push_pending_frames+0xa0/0x230 [ 23.870861] tcp_send_fin+0x154/0xbc0 [ 23.874648] tcp_close+0xc62/0xf40 [ 23.878171] inet_release+0xe9/0x1c0 [ 23.881876] __sock_release+0xd2/0x2c0 [ 23.885750] ? __sock_release+0x2c0/0x2c0 [ 23.889891] sock_close+0x15/0x20 [ 23.893881] __fput+0x25e/0x710 [ 23.897162] task_work_run+0x125/0x1a0 [ 23.901037] do_exit+0x9cb/0x2a20 [ 23.904561] ? mm_update_next_owner+0x610/0x610 [ 23.909217] do_group_exit+0x100/0x2e0 [ 23.913101] SyS_exit_group+0x19/0x20 [ 23.916878] ? do_group_exit+0x2e0/0x2e0 [ 23.920922] do_syscall_64+0x19b/0x520 [ 23.924816] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 23.929984] RIP: 0033:0x440b48 [ 23.933154] RSP: 002b:00007ffeb4c05b18 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 23.940872] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b48 [ 23.948122] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 23.955373] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 23.962749] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 23.970004] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 23.978171] Kernel Offset: 0xb200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 23.989113] Rebooting in 86400 seconds..