audit: type=1400 audit(1569411373.336:37): avc: denied { create } for pid=7436 comm="syz-executor217" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 ================================================================== BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:193 [inline] BUG: KASAN: use-after-free in task_css include/linux/cgroup.h:482 [inline] BUG: KASAN: use-after-free in pids_release+0x228/0x250 kernel/cgroup/pids.c:252 Read of size 8 at addr ffff88808872b388 by task syz-executor217/7435 CPU: 1 PID: 7435 Comm: syz-executor217 Not tainted 4.19.75 #0 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 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __read_once_size include/linux/compiler.h:193 [inline] task_css include/linux/cgroup.h:482 [inline] pids_release+0x228/0x250 kernel/cgroup/pids.c:252 cgroup_release+0x101/0x4a0 kernel/cgroup/cgroup.c:5730 release_task+0x194/0x1630 kernel/exit.c:197 wait_task_zombie kernel/exit.c:1164 [inline] wait_consider_task+0x2c95/0x3910 kernel/exit.c:1391 do_wait_thread kernel/exit.c:1454 [inline] do_wait+0x439/0x9d0 kernel/exit.c:1525 kernel_wait4+0x171/0x290 kernel/exit.c:1668 __do_sys_wait4+0x147/0x160 kernel/exit.c:1680 __se_sys_wait4 kernel/exit.c:1676 [inline] __x64_sys_wait4+0x97/0xf0 kernel/exit.c:1676 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x40240a Code: c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 8b 05 4e 87 2d 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 d0 ff ff ff f7 RSP: 002b:00007fff65420c88 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: ffffffffffffffda RBX: 0000000000001d0c RCX: 000000000040240a RDX: 0000000040000000 RSI: 00007fff65420c94 RDI: ffffffffffffffff RBP: 00000000006d3018 R08: 0000000000000000 R09: 000055555649c880 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004033c0 R13: 0000000000403450 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 7435: 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 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc_node+0x144/0x710 mm/slab.c:3649 alloc_task_struct_node kernel/fork.c:157 [inline] dup_task_struct kernel/fork.c:802 [inline] copy_process.part.0+0x1ce0/0x7a30 kernel/fork.c:1732 copy_process kernel/fork.c:1689 [inline] _do_fork+0x257/0xfd0 kernel/fork.c:2202 __do_sys_clone kernel/fork.c:2309 [inline] __se_sys_clone kernel/fork.c:2303 [inline] __x64_sys_clone+0xbf/0x150 kernel/fork.c:2303 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7438: 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] kmem_cache_free+0x86/0x260 mm/slab.c:3765 free_task_struct kernel/fork.c:162 [inline] free_task+0xdd/0x120 kernel/fork.c:416 __put_task_struct+0x20f/0x4c0 kernel/fork.c:689 put_task_struct include/linux/sched/task.h:96 [inline] finish_task_switch+0x52b/0x780 kernel/sched/core.c:2710 context_switch kernel/sched/core.c:2829 [inline] __schedule+0x86e/0x1dc0 kernel/sched/core.c:3474 schedule+0x92/0x1c0 kernel/sched/core.c:3518 worker_thread+0x248/0xe40 kernel/workqueue.c:2317 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 The buggy address belongs to the object at ffff88808872a2c0 which belongs to the cache task_struct of size 6080 The buggy address is located 4296 bytes inside of 6080-byte region [ffff88808872a2c0, ffff88808872ba80) The buggy address belongs to the page: page:ffffea000221ca80 count:1 mapcount:0 mapping:ffff88812c26d800 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000008100(slab|head) raw: 01fffc0000008100 ffffea00027f5888 ffffea00021ce188 ffff88812c26d800 raw: 0000000000000000 ffff88808872a2c0 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808872b280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808872b300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88808872b380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808872b400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808872b480: fb fb fb fb fb fb fb fb fb fb fb fb fb 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