================================================================== BUG: KASAN: use-after-free in tcp_probe_timer net/ipv4/tcp_timer.c:360 [inline] BUG: KASAN: use-after-free in tcp_write_timer_handler+0x8c6/0x8d0 net/ipv4/tcp_timer.c:596 Read of size 4 at addr ffff8880888866d0 by task syz-fuzzer/9866 CPU: 1 PID: 9866 Comm: syz-fuzzer Not tainted 5.3.0-rc6+ #181 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482 kasan_report+0x12/0x17 mm/kasan/common.c:618 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131 tcp_probe_timer net/ipv4/tcp_timer.c:360 [inline] tcp_write_timer_handler+0x8c6/0x8d0 net/ipv4/tcp_timer.c:596 tcp_write_timer+0xa8/0x1e0 net/ipv4/tcp_timer.c:612 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1322 expire_timers kernel/time/timer.c:1366 [inline] __run_timers kernel/time/timer.c:1685 [inline] __run_timers kernel/time/timer.c:1653 [inline] run_timer_softirq+0x697/0x17a0 kernel/time/timer.c:1698 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:537 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1133 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 RIP: 0033:0x41df4a Code: 4c 24 44 48 8b 54 24 60 48 8b 9c 24 80 00 00 00 48 8b b4 24 a8 00 00 00 48 8b 7c 24 58 41 89 c8 4c 8b 54 24 50 e9 1f ff ff ff <48> 89 0c 24 48 8b 8c 24 a8 00 00 00 48 89 4c 24 08 48 8b 7c 24 58 RSP: 002b:000000c42014fe80 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 000000c41feb039b RBX: 0000000000000032 RCX: 000000c4229f8c80 RDX: 00007f71955c55f0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 000000c42014ff18 R08: 0000000000000001 R09: 0000000001b4c580 R10: 0000000000000080 R11: 000000c4229f8c80 R12: 0000000000000001 R13: 000000c428e60c60 R14: 0000000000000001 R15: 0000000000000000 Allocated by task 9882: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:493 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:501 slab_post_alloc_hook mm/slab.h:520 [inline] slab_alloc mm/slab.c:3319 [inline] kmem_cache_alloc+0x121/0x710 mm/slab.c:3483 kmem_cache_zalloc include/linux/slab.h:738 [inline] net_alloc net/core/net_namespace.c:410 [inline] copy_net_ns+0xf1/0x41f net/core/net_namespace.c:462 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202 ksys_unshare+0x444/0x980 kernel/fork.c:2831 __do_sys_unshare kernel/fork.c:2899 [inline] __se_sys_unshare kernel/fork.c:2897 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:2897 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 2592: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463 __cache_free mm/slab.c:3425 [inline] kmem_cache_free+0x86/0x320 mm/slab.c:3693 net_free net/core/net_namespace.c:438 [inline] net_drop_ns.part.0+0x70/0x90 net/core/net_namespace.c:445 net_drop_ns net/core/net_namespace.c:444 [inline] cleanup_net+0x774/0xa60 net/core/net_namespace.c:613 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 The buggy address belongs to the object at ffff888088886100 which belongs to the cache net_namespace of size 6784 The buggy address is located 1488 bytes inside of 6784-byte region [ffff888088886100, ffff888088887b80) The buggy address belongs to the page: page:ffffea0002222180 refcount:1 mapcount:0 mapping:ffff88821b69e1c0 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea0002275a08 ffffea0001b87408 ffff88821b69e1c0 raw: 0000000000000000 ffff888088886100 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888088886580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888088886600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888088886680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888088886700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888088886780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================