[....] Starting enhanced syslogd: rsyslogd[ 13.913986] audit: type=1400 audit(1516124339.756:4): avc: denied { syslog } for pid=3180 comm="rsyslogd" capability=34 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=capability2 permissive=1 [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] 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 Warning: Permanently added '10.128.0.14' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 27.756442] ================================================================== [ 27.763857] BUG: KASAN: use-after-free in sg_remove_request+0x103/0x120 [ 27.770598] Read of size 8 at addr ffff8801cd59f040 by task syzkaller040432/3338 [ 27.778105] [ 27.779715] CPU: 1 PID: 3338 Comm: syzkaller040432 Not tainted 4.9.76-g8dec074 #13 [ 27.787567] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.796892] ffff8801c7def9b0 ffffffff81d93169 ffffea00073567c0 ffff8801cd59f040 [ 27.804899] 0000000000000000 ffff8801cd59f040 ffff8801c7d84438 ffff8801c7def9e8 [ 27.812877] ffffffff8153cb43 ffff8801cd59f040 0000000000000008 0000000000000000 [ 27.820854] Call Trace: [ 27.823419] [] dump_stack+0xc1/0x128 [ 27.828758] [] print_address_description+0x73/0x280 [ 27.835394] [] kasan_report+0x275/0x360 [ 27.840989] [] ? sg_remove_request+0x103/0x120 [ 27.847203] [] __asan_report_load8_noabort+0x14/0x20 [ 27.853927] [] sg_remove_request+0x103/0x120 [ 27.859954] [] sg_finish_rem_req+0x295/0x340 [ 27.865983] [] sg_read+0xa1c/0x1440 [ 27.871230] [] ? sg_proc_seq_show_debug+0xd10/0xd10 [ 27.877876] [] ? fsnotify+0xf30/0xf30 [ 27.883306] [] ? avc_policy_seqno+0x9/0x20 [ 27.889164] [] do_loop_readv_writev.part.17+0x141/0x1e0 [ 27.896147] [] ? security_file_permission+0x89/0x1e0 [ 27.902900] [] ? sg_proc_seq_show_debug+0xd10/0xd10 [ 27.909534] [] ? sg_proc_seq_show_debug+0xd10/0xd10 [ 27.916170] [] do_readv_writev+0x520/0x750 [ 27.922026] [] ? vfs_write+0x530/0x530 [ 27.927534] [] ? __fget+0x201/0x3a0 [ 27.932791] [] ? __fget+0x228/0x3a0 [ 27.938039] [] ? __fget+0x47/0x3a0 [ 27.943204] [] vfs_readv+0x84/0xc0 [ 27.948375] [] do_readv+0xe6/0x250 [ 27.953536] [] ? vfs_readv+0xc0/0xc0 [ 27.958875] [] ? entry_SYSCALL_64_fastpath+0x5/0xe2 [ 27.965528] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 27.972340] [] SyS_readv+0x27/0x30 [ 27.977504] [] entry_SYSCALL_64_fastpath+0x23/0xe2 [ 27.984055] [ 27.985656] Allocated by task 3334: [ 27.989258] save_stack_trace+0x16/0x20 [ 27.993202] save_stack+0x43/0xd0 [ 27.996625] kasan_kmalloc+0xad/0xe0 [ 28.000309] kasan_slab_alloc+0x12/0x20 [ 28.004256] kmem_cache_alloc+0xba/0x290 [ 28.008289] skb_clone+0x142/0x2c0 [ 28.011802] dev_queue_xmit_nit+0x29f/0x870 [ 28.016094] dev_hard_start_xmit+0xa6/0x8a0 [ 28.020399] sch_direct_xmit+0x2bc/0x5d0 [ 28.024427] __dev_queue_xmit+0x15fd/0x1e60 [ 28.028719] dev_queue_xmit+0x17/0x20 [ 28.032492] ip_finish_output2+0xbe8/0x1060 [ 28.036785] ip_finish_output+0x6b1/0xa00 [ 28.040903] ip_output+0x1ca/0x610 [ 28.044412] ip_local_out+0x95/0x170 [ 28.048098] ip_queue_xmit+0x884/0x1760 [ 28.052046] tcp_transmit_skb+0x1847/0x2f00 [ 28.056337] tcp_write_xmit+0xbd6/0x4a40 [ 28.060366] __tcp_push_pending_frames+0xa0/0x240 [ 28.065179] tcp_push+0x3fc/0x5d0 [ 28.068602] tcp_sendmsg+0xb38/0x2ff0 [ 28.072374] inet_sendmsg+0x2bc/0x4c0 [ 28.076146] sock_sendmsg+0xca/0x110 [ 28.079830] sock_write_iter+0x226/0x3b0 [ 28.083864] __vfs_write+0x4bf/0x680 [ 28.087548] vfs_write+0x189/0x530 [ 28.091061] SyS_write+0xd9/0x1b0 [ 28.094487] entry_SYSCALL_64_fastpath+0x23/0xe2 [ 28.099211] [ 28.100821] Freed by task 3334: [ 28.104073] save_stack_trace+0x16/0x20 [ 28.108018] save_stack+0x43/0xd0 [ 28.111444] kasan_slab_free+0x72/0xc0 [ 28.115300] kmem_cache_free+0xc7/0x300 [ 28.119246] kfree_skbmem+0xd7/0xf0 [ 28.122846] __kfree_skb+0x1d/0x20 [ 28.126355] kfree_skb+0xcc/0x330 [ 28.129780] packet_rcv_spkt+0xda/0x4c0 [ 28.133725] dev_queue_xmit_nit+0x5ab/0x870 [ 28.138021] dev_hard_start_xmit+0xa6/0x8a0 [ 28.142325] sch_direct_xmit+0x2bc/0x5d0 [ 28.146357] __dev_queue_xmit+0x15fd/0x1e60 [ 28.150651] dev_queue_xmit+0x17/0x20 [ 28.154424] ip_finish_output2+0xbe8/0x1060 [ 28.158714] ip_finish_output+0x6b1/0xa00 [ 28.162832] ip_output+0x1ca/0x610 [ 28.166343] ip_local_out+0x95/0x170 [ 28.170029] ip_queue_xmit+0x884/0x1760 [ 28.173978] tcp_transmit_skb+0x1847/0x2f00 [ 28.178268] tcp_write_xmit+0xbd6/0x4a40 [ 28.182308] __tcp_push_pending_frames+0xa0/0x240 [ 28.187122] tcp_push+0x3fc/0x5d0 [ 28.190547] tcp_sendmsg+0xb38/0x2ff0 [ 28.194330] inet_sendmsg+0x2bc/0x4c0 [ 28.198105] sock_sendmsg+0xca/0x110 [ 28.201787] sock_write_iter+0x226/0x3b0 [ 28.205820] __vfs_write+0x4bf/0x680 [ 28.209502] vfs_write+0x189/0x530 [ 28.213013] SyS_write+0xd9/0x1b0 [ 28.216441] entry_SYSCALL_64_fastpath+0x23/0xe2 [ 28.221167] [ 28.222768] The buggy address belongs to the object at ffff8801cd59f000 [ 28.222768] which belongs to the cache skbuff_head_cache of size 224 [ 28.235914] The buggy address is located 64 bytes inside of [ 28.235914] 224-byte region [ffff8801cd59f000, ffff8801cd59f0e0) [ 28.247671] The buggy address belongs to the page: [ 28.252575] page:ffffea00073567c0 count:1 mapcount:0 mapping: (null) index:0x0 [ 28.260804] flags: 0x8000000000000080(slab) [ 28.265094] page dumped because: kasan: bad access detected [ 28.270773] [ 28.272370] Memory state around the buggy address: [ 28.277270] ffff8801cd59ef00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc [ 28.284601] ffff8801cd59ef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 28.291930] >ffff8801cd59f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.299257] ^ [ 28.304677] ffff8801cd59f080: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 28.312005] ffff8801cd59f100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 28.319335] ================================================================== [ 28.326671] Disabling lock debugging due to kernel taint [ 28.332667] Kernel panic - not syncing: panic_on_warn set ... [ 28.332667] [ 28.342644] CPU: 1 PID: 3338 Comm: syzkaller040432 Tainted: G B 4.9.76-g8dec074 #13 [ 28.351549] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.360885] ffff8801c7def908 ffffffff81d93169 ffffffff84195c2f ffff8801c7def9e0 [ 28.368876] 0000000000000000 ffff8801cd59f040 ffff8801c7d84438 ffff8801c7def9d0 [ 28.376856] ffffffff8142e371 0000000041b58ab3 ffffffff84189690 ffffffff8142e1b5 [ 28.384860] Call Trace: [ 28.387426] [] dump_stack+0xc1/0x128 [ 28.392765] [] panic+0x1bc/0x3a8 [ 28.397757] [] ? percpu_up_read_preempt_enable.constprop.53+0xd7/0xd7 [ 28.405961] [] ? preempt_schedule+0x25/0x30 [ 28.411921] [] ? ___preempt_schedule+0x16/0x18 [ 28.418136] [] kasan_end_report+0x50/0x50 [ 28.423905] [] kasan_report+0x167/0x360 [ 28.429501] [] ? sg_remove_request+0x103/0x120 [ 28.435703] [] __asan_report_load8_noabort+0x14/0x20 [ 28.442430] [] sg_remove_request+0x103/0x120 [ 28.448460] [] sg_finish_rem_req+0x295/0x340 [ 28.454488] [] sg_read+0xa1c/0x1440 [ 28.459738] [] ? sg_proc_seq_show_debug+0xd10/0xd10 [ 28.466376] [] ? fsnotify+0xf30/0xf30 [ 28.471799] [] ? avc_policy_seqno+0x9/0x20 [ 28.477659] [] do_loop_readv_writev.part.17+0x141/0x1e0 [ 28.484640] [] ? security_file_permission+0x89/0x1e0 [ 28.491536] [] ? sg_proc_seq_show_debug+0xd10/0xd10 [ 28.498176] [] ? sg_proc_seq_show_debug+0xd10/0xd10 [ 28.504813] [] do_readv_writev+0x520/0x750 [ 28.510689] [] ? vfs_write+0x530/0x530 [ 28.516196] [] ? __fget+0x201/0x3a0 [ 28.521443] [] ? __fget+0x228/0x3a0 [ 28.527269] [] ? __fget+0x47/0x3a0 [ 28.532436] [] vfs_readv+0x84/0xc0 [ 28.537596] [] do_readv+0xe6/0x250 [ 28.542759] [] ? vfs_readv+0xc0/0xc0 [ 28.548097] [] ? entry_SYSCALL_64_fastpath+0x5/0xe2 [ 28.554739] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 28.561547] [] SyS_readv+0x27/0x30 [ 28.566707] [] entry_SYSCALL_64_fastpath+0x23/0xe2 [ 28.573678] Dumping ftrace buffer: [ 28.577201] (ftrace buffer empty) [ 28.581064] Kernel Offset: disabled [ 28.584664] Rebooting in 86400 seconds..