================================================================== BUG: KASAN: use-after-free in atomic_dec include/asm-generic/atomic-instrumented.h:114 [inline] BUG: KASAN: use-after-free in free_htab_elem+0x23/0x40 kernel/bpf/sockmap.c:224 Write of size 4 at addr ffff8801c6060408 by task syz-executor1/7489 CPU: 1 PID: 7489 Comm: syz-executor1 Not tainted 4.17.0+ #39 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+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_dec include/asm-generic/atomic-instrumented.h:114 [inline] free_htab_elem+0x23/0x40 kernel/bpf/sockmap.c:224 bpf_tcp_close+0x8c1/0xf80 kernel/bpf/sockmap.c:273 inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459 __sock_release+0xd7/0x260 net/socket.c:603 sock_close+0x19/0x20 net/socket.c:1186 __fput+0x353/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1aee/0x2730 kernel/exit.c:865 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2468 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2cf/0x360 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455b29 Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f6aec903ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000000 RBX: 000000000072bec8 RCX: 0000000000455b29 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072bec8 RBP: 000000000072bec8 R08: 0000000000000000 R09: 000000000072bea0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe601932ef R14: 00007f6aec9049c0 R15: 0000000000000000 Allocated by task 7505: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:706 [inline] sock_hash_alloc+0x20d/0x6a0 kernel/bpf/sockmap.c:2003 find_and_alloc_map kernel/bpf/syscall.c:129 [inline] map_create+0x393/0x1010 kernel/bpf/syscall.c:453 __do_sys_bpf kernel/bpf/syscall.c:2351 [inline] __se_sys_bpf kernel/bpf/syscall.c:2328 [inline] __x64_sys_bpf+0x303/0x510 kernel/bpf/syscall.c:2328 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 27: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xd9/0x260 mm/slab.c:3813 sock_hash_free+0x51c/0x6e0 kernel/bpf/sockmap.c:2098 bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262 process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153 worker_thread+0x181/0x13a0 kernel/workqueue.c:2296 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 The buggy address belongs to the object at ffff8801c6060300 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 264 bytes inside of 512-byte region [ffff8801c6060300, ffff8801c6060500) The buggy address belongs to the page: page:ffffea0007181800 count:1 mapcount:0 mapping:ffff8801da800940 index:0xffff8801c6060a80 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea00071fd608 ffffea00073fcfc8 ffff8801da800940 raw: ffff8801c6060a80 ffff8801c6060080 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801c6060300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c6060380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801c6060400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801c6060480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c6060500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================