audit: type=1400 audit(1567164190.356:37): avc: denied { write } for pid=7556 comm="syz-executor545" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:unlabeled_t:s0 tclass=socket permissive=1 ================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x7b/0x200 lib/refcount.c:120 Read of size 4 at addr ffff8880876a7400 by task syz-executor545/7558 CPU: 0 PID: 7558 Comm: syz-executor545 Not tainted 4.19.69 #43 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+0x7c/0x20d mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x123/0x190 mm/kasan/kasan.c:267 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] refcount_inc_not_zero_checked+0x7b/0x200 lib/refcount.c:120 refcount_inc_checked+0x17/0x70 lib/refcount.c:153 sock_hold include/net/sock.h:647 [inline] nr_release+0x62/0x3b0 net/netrom/af_netrom.c:523 __sock_release+0xce/0x2a0 net/socket.c:579 sock_close+0x1b/0x30 net/socket.c:1140 __fput+0x2dd/0x8b0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x145/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x994/0x2fa0 kernel/exit.c:876 do_group_exit+0x135/0x370 kernel/exit.c:979 get_signal+0x3ec/0x1fc0 kernel/signal.c:2574 do_signal+0x95/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x442af9 Code: Bad RIP value. RSP: 002b:00007fff602788d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002b RAX: fffffffffffffe00 RBX: 0000000000000004 RCX: 0000000000442af9 RDX: 0000000020000080 RSI: 0000000020000280 RDI: 0000000000000004 RBP: 0000000000000003 R08: 00000000004aa07a R09: 00000000004aa07a R10: 00000000004aa07a R11: 0000000000000246 R12: 00000000015fd850 R13: 0000000000000016 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 7558: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531 __do_kmalloc mm/slab.c:3727 [inline] __kmalloc+0x15d/0x750 mm/slab.c:3736 kmalloc include/linux/slab.h:520 [inline] sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1466 sk_alloc+0x39/0xf70 net/core/sock.c:1520 nr_create+0xb9/0x5e0 net/netrom/af_netrom.c:436 __sock_create+0x3d8/0x730 net/socket.c:1276 sock_create net/socket.c:1316 [inline] __sys_socket+0x103/0x220 net/socket.c:1346 __do_sys_socket net/socket.c:1355 [inline] __se_sys_socket net/socket.c:1353 [inline] __x64_sys_socket+0x73/0xb0 net/socket.c:1353 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7558: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kfree+0xcf/0x220 mm/slab.c:3822 sk_prot_free net/core/sock.c:1503 [inline] __sk_destruct+0x4ef/0x6d0 net/core/sock.c:1585 sk_destruct+0x7b/0x90 net/core/sock.c:1593 __sk_free+0xce/0x300 net/core/sock.c:1604 sk_free+0x42/0x50 net/core/sock.c:1615 sock_put include/net/sock.h:1702 [inline] nr_release+0x332/0x3b0 net/netrom/af_netrom.c:557 __sock_release+0xce/0x2a0 net/socket.c:579 sock_close+0x1b/0x30 net/socket.c:1140 __fput+0x2dd/0x8b0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x145/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x994/0x2fa0 kernel/exit.c:876 do_group_exit+0x135/0x370 kernel/exit.c:979 get_signal+0x3ec/0x1fc0 kernel/signal.c:2574 do_signal+0x95/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880876a7380 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 128 bytes inside of 2048-byte region [ffff8880876a7380, ffff8880876a7b80) The buggy address belongs to the page: page:ffffea00021da980 count:1 mapcount:0 mapping:ffff88812c3f0c40 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000008100(slab|head) raw: 01fffc0000008100 ffffea000226b808 ffffea0001e51d88 ffff88812c3f0c40 raw: 0000000000000000 ffff8880876a6280 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880876a7300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880876a7380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880876a7400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880876a7480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880876a7500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================