================================================================== BUG: KASAN: use-after-free in tcp_retransmit_timer+0x245f/0x28c0 net/ipv4/tcp_timer.c:471 Read of size 8 at addr ffff888048afc4b8 by task syz-executor.3/15983 CPU: 0 PID: 15983 Comm: syz-executor.3 Not tainted 4.14.232-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351 kasan_report mm/kasan/report.c:409 [inline] __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430 tcp_retransmit_timer+0x245f/0x28c0 net/ipv4/tcp_timer.c:471 tcp_write_timer_handler+0x434/0x780 net/ipv4/tcp_timer.c:583 tcp_write_timer+0xc8/0x160 net/ipv4/tcp_timer.c:601 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1280 expire_timers+0x232/0x4d0 kernel/time/timer.c:1319 __run_timers kernel/time/timer.c:1637 [inline] run_timer_softirq+0x1d5/0x5a0 kernel/time/timer.c:1650 __do_softirq+0x24d/0x9ff kernel/softirq.c:288 invoke_softirq kernel/softirq.c:368 [inline] irq_exit+0x193/0x240 kernel/softirq.c:409 exiting_irq arch/x86/include/asm/apic.h:638 [inline] smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1106 apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:793 RIP: 0010:slow_down_io arch/x86/include/asm/paravirt.h:268 [inline] RIP: 0010:inb_p arch/x86/include/asm/io.h:309 [inline] RIP: 0010:vga_io_r include/video/vga.h:204 [inline] RIP: 0010:vga_io_rgfx include/video/vga.h:389 [inline] RIP: 0010:selectmask drivers/video/fbdev/vga16fb.c:132 [inline] RIP: 0010:vga_imageblit_expand drivers/video/fbdev/vga16fb.c:1166 [inline] RIP: 0010:vga16fb_imageblit+0x957/0x2140 drivers/video/fbdev/vga16fb.c:1261 RSP: 0018:ffff88809eacf000 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: dffffc00000000ff RBX: 0000000000000007 RCX: ffffc90009ff7000 RDX: 00000000000003cf RSI: ffffffff833c9aa2 RDI: ffff88809eacf1a8 RBP: ffff88809eacf19c R08: 0000000000000006 R09: 0000000000000000 R10: 0000000000000006 R11: 0000000000000000 R12: ffff888238c9c5d0 R13: ffff88809eacf198 R14: ffff8880b0a64870 R15: 0000000000000000 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:139 [inline] bit_putcs+0x81e/0xc30 drivers/video/fbdev/core/bitblit.c:188 fbcon_putcs+0x2fe/0x480 drivers/video/fbdev/core/fbcon.c:1247 fbcon_redraw.constprop.0+0x3e8/0x460 drivers/video/fbdev/core/fbcon.c:1624 fbcon_scroll+0x381/0x31e0 drivers/video/fbdev/core/fbcon.c:1735 con_scroll+0x2c5/0x360 drivers/tty/vt/vt.c:327 lf+0x226/0x270 drivers/tty/vt/vt.c:1141 do_con_trol+0x150/0x51e0 drivers/tty/vt/vt.c:1804 do_con_write+0x9fb/0x19b0 drivers/tty/vt/vt.c:2454 con_write+0x21/0xa0 drivers/tty/vt/vt.c:2805 do_output_char+0x4f5/0x750 drivers/tty/n_tty.c:447 process_output drivers/tty/n_tty.c:514 [inline] n_tty_write+0x3e3/0xda0 drivers/tty/n_tty.c:2345 do_tty_write drivers/tty/tty_io.c:959 [inline] tty_write+0x410/0x740 drivers/tty/tty_io.c:1043 __vfs_write+0xe4/0x630 fs/read_write.c:480 __kernel_write+0xf5/0x330 fs/read_write.c:501 write_pipe_buf+0x143/0x1c0 fs/splice.c:797 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x326/0x7a0 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] default_file_splice_write+0xc5/0x150 fs/splice.c:809 do_splice_from fs/splice.c:851 [inline] direct_splice_actor+0x115/0x160 fs/splice.c:1018 splice_direct_to_actor+0x27c/0x730 fs/splice.c:973 do_splice_direct+0x164/0x210 fs/splice.c:1061 do_sendfile+0x47f/0xb30 fs/read_write.c:1441 SYSC_sendfile64 fs/read_write.c:1502 [inline] SyS_sendfile64+0xff/0x110 fs/read_write.c:1488 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4665f9 RSP: 002b:00007fd0582d7188 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004 RBP: 00000000004bfce1 R08: 0000000000000000 R09: 0000000000000000 R10: 0800000080004103 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffc5dd085ef R14: 00007fd0582d7300 R15: 0000000000022000 Allocated by task 10827: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551 kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552 kmem_cache_zalloc include/linux/slab.h:651 [inline] net_alloc net/core/net_namespace.c:362 [inline] copy_net_ns+0xf7/0x440 net/core/net_namespace.c:402 create_new_namespaces+0x375/0x720 kernel/nsproxy.c:107 unshare_nsproxy_namespaces+0xa1/0x1d0 kernel/nsproxy.c:206 SYSC_unshare kernel/fork.c:2412 [inline] SyS_unshare+0x308/0x7f0 kernel/fork.c:2362 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 12891: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758 net_free net/core/net_namespace.c:378 [inline] net_drop_ns+0x63/0x70 net/core/net_namespace.c:385 cleanup_net+0x526/0x840 net/core/net_namespace.c:502 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 The buggy address belongs to the object at ffff888048afc2c0 which belongs to the cache net_namespace of size 8832 The buggy address is located 504 bytes inside of 8832-byte region [ffff888048afc2c0, ffff888048afe540) The buggy address belongs to the page: page:ffffea000122bf00 count:1 mapcount:0 mapping:ffff888048afc2c0 index:0x0 compound_mapcount: 0 flags: 0xfff00000008100(slab|head) raw: 00fff00000008100 ffff888048afc2c0 0000000000000000 0000000100000001 raw: ffffea000118f920 ffffea0000fc9920 ffff8880b5f93b40 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888048afc380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888048afc400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888048afc480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888048afc500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888048afc580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================