[ 10.112244] random: sshd: uninitialized urandom read (32 bytes read) [....] 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: [ 34.415984] random: sshd: uninitialized urandom read (32 bytes read) [ 34.693844] audit: type=1400 audit(1568123243.991:6): avc: denied { map } for pid=1767 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 [ 34.736273] random: sshd: uninitialized urandom read (32 bytes read) [ 35.233737] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.20' (ECDSA) to the list of known hosts. [ 40.941129] urandom_read: 1 callbacks suppressed [ 40.941134] random: sshd: uninitialized urandom read (32 bytes read) [ 41.041147] audit: type=1400 audit(1568123250.341:7): avc: denied { map } for pid=1785 comm="syz-executor455" path="/root/syz-executor455009786" 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 [ 41.790774] ================================================================== [ 41.798275] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 41.805009] Read of size 2 at addr ffff8881d01707b0 by task syz-executor455/1786 [ 41.812516] [ 41.814122] CPU: 1 PID: 1786 Comm: syz-executor455 Not tainted 4.14.143+ #0 [ 41.821196] Call Trace: [ 41.823778] dump_stack+0xca/0x134 [ 41.827305] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.831705] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.836099] print_address_description+0x60/0x226 [ 41.840938] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.845337] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.849726] __kasan_report.cold+0x1a/0x41 [ 41.853942] ? kvm_guest_cpu_init+0x220/0x220 [ 41.858414] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.862819] tcp_init_tso_segs+0x19d/0x1f0 [ 41.867047] ? tcp_tso_segs+0x7b/0x1c0 [ 41.870913] tcp_write_xmit+0x15a/0x4730 [ 41.874961] ? memset+0x20/0x40 [ 41.878226] __tcp_push_pending_frames+0xa0/0x230 [ 41.883175] tcp_send_fin+0x154/0xbc0 [ 41.886962] tcp_close+0xc62/0xf40 [ 41.890486] inet_release+0xe9/0x1c0 [ 41.894265] __sock_release+0xd2/0x2c0 [ 41.898306] ? __sock_release+0x2c0/0x2c0 [ 41.902431] sock_close+0x15/0x20 [ 41.905874] __fput+0x25e/0x710 [ 41.909138] task_work_run+0x125/0x1a0 [ 41.913014] do_exit+0x9cb/0x2a20 [ 41.916451] ? mm_update_next_owner+0x610/0x610 [ 41.921109] do_group_exit+0x100/0x2e0 [ 41.924977] SyS_exit_group+0x19/0x20 [ 41.928754] ? do_group_exit+0x2e0/0x2e0 [ 41.932791] do_syscall_64+0x19b/0x520 [ 41.936675] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.941842] RIP: 0033:0x440608 [ 41.945010] RSP: 002b:00007ffd60fa1688 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.952696] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440608 [ 41.959942] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 41.967215] RBP: 00000000004c6950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 41.974479] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 41.981732] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 41.989004] [ 41.990613] Allocated by task 1786: [ 41.994222] __kasan_kmalloc.part.0+0x53/0xc0 [ 41.998696] kmem_cache_alloc+0xee/0x360 [ 42.002735] __alloc_skb+0xea/0x5c0 [ 42.006341] sk_stream_alloc_skb+0xf4/0x8a0 [ 42.010639] tcp_sendmsg_locked+0xf11/0x2f50 [ 42.015037] tcp_sendmsg+0x2b/0x40 [ 42.018552] inet_sendmsg+0x15b/0x520 [ 42.022330] sock_sendmsg+0xb7/0x100 [ 42.026017] SyS_sendto+0x1de/0x2f0 [ 42.029637] do_syscall_64+0x19b/0x520 [ 42.033516] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.038680] 0xffffffffffffffff [ 42.041936] [ 42.043540] Freed by task 1786: [ 42.046815] __kasan_slab_free+0x164/0x210 [ 42.051027] kmem_cache_free+0xd7/0x3b0 [ 42.054976] kfree_skbmem+0x84/0x110 [ 42.058669] tcp_remove_empty_skb+0x264/0x320 [ 42.063144] tcp_sendmsg_locked+0x1c09/0x2f50 [ 42.067617] tcp_sendmsg+0x2b/0x40 [ 42.071140] inet_sendmsg+0x15b/0x520 [ 42.074937] sock_sendmsg+0xb7/0x100 [ 42.078630] SyS_sendto+0x1de/0x2f0 [ 42.082235] do_syscall_64+0x19b/0x520 [ 42.086117] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.091282] 0xffffffffffffffff [ 42.094547] [ 42.096152] The buggy address belongs to the object at ffff8881d0170780 [ 42.096152] which belongs to the cache skbuff_fclone_cache of size 456 [ 42.109491] The buggy address is located 48 bytes inside of [ 42.109491] 456-byte region [ffff8881d0170780, ffff8881d0170948) [ 42.121254] The buggy address belongs to the page: [ 42.126162] page:ffffea0007405c00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 42.139075] flags: 0x4000000000010200(slab|head) [ 42.143812] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 42.151684] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 42.159539] page dumped because: kasan: bad access detected [ 42.165337] [ 42.166940] Memory state around the buggy address: [ 42.171845] ffff8881d0170680: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 42.179192] ffff8881d0170700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 42.186526] >ffff8881d0170780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.193861] ^ [ 42.198766] ffff8881d0170800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.206111] ffff8881d0170880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.213445] ================================================================== [ 42.220780] Disabling lock debugging due to kernel taint [ 42.228187] Kernel panic - not syncing: panic_on_warn set ... [ 42.228187] [ 42.235653] CPU: 1 PID: 1786 Comm: syz-executor455 Tainted: G B 4.14.143+ #0 [ 42.243944] Call Trace: [ 42.246513] dump_stack+0xca/0x134 [ 42.250061] panic+0x1ea/0x3d3 [ 42.253244] ? add_taint.cold+0x16/0x16 [ 42.257197] ? tcp_init_tso_segs+0x19d/0x1f0 [ 42.261588] ? ___preempt_schedule+0x16/0x18 [ 42.265981] ? tcp_init_tso_segs+0x19d/0x1f0 [ 42.270453] end_report+0x43/0x49 [ 42.273882] ? tcp_init_tso_segs+0x19d/0x1f0 [ 42.278266] __kasan_report.cold+0xd/0x41 [ 42.282393] ? kvm_guest_cpu_init+0x220/0x220 [ 42.286861] ? tcp_init_tso_segs+0x19d/0x1f0 [ 42.291248] tcp_init_tso_segs+0x19d/0x1f0 [ 42.295457] ? tcp_tso_segs+0x7b/0x1c0 [ 42.299320] tcp_write_xmit+0x15a/0x4730 [ 42.303374] ? memset+0x20/0x40 [ 42.306706] __tcp_push_pending_frames+0xa0/0x230 [ 42.311581] tcp_send_fin+0x154/0xbc0 [ 42.315399] tcp_close+0xc62/0xf40 [ 42.318940] inet_release+0xe9/0x1c0 [ 42.322642] __sock_release+0xd2/0x2c0 [ 42.326522] ? __sock_release+0x2c0/0x2c0 [ 42.330663] sock_close+0x15/0x20 [ 42.334096] __fput+0x25e/0x710 [ 42.337357] task_work_run+0x125/0x1a0 [ 42.341227] do_exit+0x9cb/0x2a20 [ 42.344675] ? mm_update_next_owner+0x610/0x610 [ 42.349337] do_group_exit+0x100/0x2e0 [ 42.353216] SyS_exit_group+0x19/0x20 [ 42.357004] ? do_group_exit+0x2e0/0x2e0 [ 42.361071] do_syscall_64+0x19b/0x520 [ 42.364938] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 42.370103] RIP: 0033:0x440608 [ 42.373281] RSP: 002b:00007ffd60fa1688 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 42.380969] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440608 [ 42.388219] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 42.395484] RBP: 00000000004c6950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 42.402747] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 42.409994] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 42.417926] Kernel Offset: 0x29000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 42.428827] Rebooting in 86400 seconds..