[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 41.764458] random: sshd: uninitialized urandom read (32 bytes read) [ 42.236086] kauditd_printk_skb: 9 callbacks suppressed [ 42.236094] audit: type=1400 audit(1568989503.501:35): avc: denied { map } for pid=6844 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 [ 42.296423] random: sshd: uninitialized urandom read (32 bytes read) [ 42.840376] random: sshd: uninitialized urandom read (32 bytes read) [ 43.032585] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.53' (ECDSA) to the list of known hosts. [ 48.579613] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 48.690709] audit: type=1400 audit(1568989509.961:36): avc: denied { map } for pid=6856 comm="syz-executor289" path="/root/syz-executor289894240" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 48.719215] ================================================================== [ 48.726926] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 [ 48.733937] Read of size 2 at addr ffff8880a95305f0 by task syz-executor289/6856 [ 48.741447] [ 48.743054] CPU: 0 PID: 6856 Comm: syz-executor289 Not tainted 4.14.145 #0 [ 48.750228] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 48.759853] Call Trace: [ 48.762441] dump_stack+0x138/0x197 [ 48.766058] ? tcp_init_tso_segs+0x1ae/0x200 [ 48.770475] print_address_description.cold+0x7c/0x1dc [ 48.775760] ? tcp_init_tso_segs+0x1ae/0x200 [ 48.780166] kasan_report.cold+0xa9/0x2af [ 48.784396] __asan_report_load2_noabort+0x14/0x20 [ 48.789315] tcp_init_tso_segs+0x1ae/0x200 [ 48.793620] ? tcp_tso_segs+0x7d/0x1c0 [ 48.797490] tcp_write_xmit+0x15e/0x4960 [ 48.801536] ? tcp_v6_md5_lookup+0x23/0x30 [ 48.805760] ? tcp_established_options+0x2c5/0x420 [ 48.810683] ? tcp_current_mss+0x1dc/0x2f0 [ 48.814913] ? __alloc_skb+0x3ee/0x500 [ 48.818783] __tcp_push_pending_frames+0xa6/0x260 [ 48.823607] tcp_send_fin+0x17e/0xc40 [ 48.827404] tcp_close+0xcc8/0xfb0 [ 48.830954] ? lock_acquire+0x16f/0x430 [ 48.834918] ? ip_mc_drop_socket+0x1d6/0x230 [ 48.839394] inet_release+0xec/0x1c0 [ 48.843099] inet6_release+0x53/0x80 [ 48.847231] __sock_release+0xce/0x2b0 [ 48.851109] ? __sock_release+0x2b0/0x2b0 [ 48.855338] sock_close+0x1b/0x30 [ 48.858798] __fput+0x275/0x7a0 [ 48.862251] ____fput+0x16/0x20 [ 48.865530] task_work_run+0x114/0x190 [ 48.869640] do_exit+0x7df/0x2c10 [ 48.873172] ? mm_update_next_owner+0x5d0/0x5d0 [ 48.877844] ? fd_install+0x4d/0x60 [ 48.881456] ? sock_map_fd+0x56/0x80 [ 48.885159] ? SyS_socket+0x103/0x170 [ 48.889041] do_group_exit+0x111/0x330 [ 48.892916] SyS_exit_group+0x1d/0x20 [ 48.896870] ? do_group_exit+0x330/0x330 [ 48.900912] do_syscall_64+0x1e8/0x640 [ 48.904796] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 48.909689] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.914860] RIP: 0033:0x43ee88 [ 48.918041] RSP: 002b:00007ffd687cff68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.925926] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 48.933591] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 48.940843] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.948093] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 48.955622] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 48.962903] [ 48.964597] Allocated by task 6856: [ 48.968208] save_stack_trace+0x16/0x20 [ 48.972164] save_stack+0x45/0xd0 [ 48.975686] kasan_kmalloc+0xce/0xf0 [ 48.979648] kasan_slab_alloc+0xf/0x20 [ 48.983732] kmem_cache_alloc_node+0x144/0x780 [ 48.988390] __alloc_skb+0x9c/0x500 [ 48.992019] sk_stream_alloc_skb+0xb3/0x780 [ 48.996327] tcp_sendmsg_locked+0xf61/0x3200 [ 49.001043] tcp_sendmsg+0x30/0x50 [ 49.004924] inet_sendmsg+0x122/0x500 [ 49.008716] sock_sendmsg+0xce/0x110 [ 49.012415] SYSC_sendto+0x206/0x310 [ 49.016111] SyS_sendto+0x40/0x50 [ 49.019557] do_syscall_64+0x1e8/0x640 [ 49.023431] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 49.028686] [ 49.030293] Freed by task 6856: [ 49.033552] save_stack_trace+0x16/0x20 [ 49.037603] save_stack+0x45/0xd0 [ 49.041222] kasan_slab_free+0x75/0xc0 [ 49.045285] kmem_cache_free+0x83/0x2b0 [ 49.049416] kfree_skbmem+0x8d/0x120 [ 49.053114] __kfree_skb+0x1e/0x30 [ 49.056928] tcp_remove_empty_skb.part.0+0x231/0x2e0 [ 49.062370] tcp_sendmsg_locked+0x1ced/0x3200 [ 49.067046] tcp_sendmsg+0x30/0x50 [ 49.070587] inet_sendmsg+0x122/0x500 [ 49.074461] sock_sendmsg+0xce/0x110 [ 49.078163] SYSC_sendto+0x206/0x310 [ 49.081996] SyS_sendto+0x40/0x50 [ 49.085448] do_syscall_64+0x1e8/0x640 [ 49.089404] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 49.095032] [ 49.096653] The buggy address belongs to the object at ffff8880a95305c0 [ 49.096653] which belongs to the cache skbuff_fclone_cache of size 472 [ 49.109987] The buggy address is located 48 bytes inside of [ 49.109987] 472-byte region [ffff8880a95305c0, ffff8880a9530798) [ 49.121859] The buggy address belongs to the page: [ 49.126869] page:ffffea0002a54c00 count:1 mapcount:0 mapping:ffff8880a95300c0 index:0x0 [ 49.135028] flags: 0x1fffc0000000100(slab) [ 49.139259] raw: 01fffc0000000100 ffff8880a95300c0 0000000000000000 0000000100000006 [ 49.147239] raw: ffffea0002947c60 ffff8880a9e1bd48 ffff8880a9e19a80 0000000000000000 [ 49.155121] page dumped because: kasan: bad access detected [ 49.160923] [ 49.162529] Memory state around the buggy address: [ 49.167522] ffff8880a9530480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 49.175126] ffff8880a9530500: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc [ 49.182579] >ffff8880a9530580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 49.189922] ^ [ 49.196924] ffff8880a9530600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.204353] ffff8880a9530680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.211690] ================================================================== [ 49.219047] Disabling lock debugging due to kernel taint [ 49.226746] Kernel panic - not syncing: panic_on_warn set ... [ 49.226746] [ 49.234295] CPU: 1 PID: 6856 Comm: syz-executor289 Tainted: G B 4.14.145 #0 [ 49.242686] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.252194] Call Trace: [ 49.254769] dump_stack+0x138/0x197 [ 49.258385] ? tcp_init_tso_segs+0x1ae/0x200 [ 49.262951] panic+0x1f2/0x426 [ 49.266136] ? add_taint.cold+0x16/0x16 [ 49.270331] ? ___preempt_schedule+0x16/0x18 [ 49.274723] kasan_end_report+0x47/0x4f [ 49.278678] kasan_report.cold+0x130/0x2af [ 49.282902] __asan_report_load2_noabort+0x14/0x20 [ 49.288770] tcp_init_tso_segs+0x1ae/0x200 [ 49.293073] ? tcp_tso_segs+0x7d/0x1c0 [ 49.298156] tcp_write_xmit+0x15e/0x4960 [ 49.302255] ? tcp_v6_md5_lookup+0x23/0x30 [ 49.306486] ? tcp_established_options+0x2c5/0x420 [ 49.311407] ? tcp_current_mss+0x1dc/0x2f0 [ 49.315660] ? __alloc_skb+0x3ee/0x500 [ 49.319647] __tcp_push_pending_frames+0xa6/0x260 [ 49.324475] tcp_send_fin+0x17e/0xc40 [ 49.328609] tcp_close+0xcc8/0xfb0 [ 49.332134] ? lock_acquire+0x16f/0x430 [ 49.336197] ? ip_mc_drop_socket+0x1d6/0x230 [ 49.340696] inet_release+0xec/0x1c0 [ 49.344390] inet6_release+0x53/0x80 [ 49.348099] __sock_release+0xce/0x2b0 [ 49.351970] ? __sock_release+0x2b0/0x2b0 [ 49.356288] sock_close+0x1b/0x30 [ 49.359828] __fput+0x275/0x7a0 [ 49.363175] ____fput+0x16/0x20 [ 49.366435] task_work_run+0x114/0x190 [ 49.370301] do_exit+0x7df/0x2c10 [ 49.373736] ? mm_update_next_owner+0x5d0/0x5d0 [ 49.378569] ? fd_install+0x4d/0x60 [ 49.382460] ? sock_map_fd+0x56/0x80 [ 49.386153] ? SyS_socket+0x103/0x170 [ 49.390467] do_group_exit+0x111/0x330 [ 49.394422] SyS_exit_group+0x1d/0x20 [ 49.398286] ? do_group_exit+0x330/0x330 [ 49.402325] do_syscall_64+0x1e8/0x640 [ 49.406189] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 49.411038] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 49.416445] RIP: 0033:0x43ee88 [ 49.419613] RSP: 002b:00007ffd687cff68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 49.427405] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 49.434670] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 49.441934] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 49.449188] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 49.456523] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 49.465841] Kernel Offset: disabled [ 49.469476] Rebooting in 86400 seconds..