================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff88809100349c by task syz-executor.2/31631 CPU: 0 PID: 31631 Comm: syz-executor.2 Not tainted 5.2.0-rc3-next-20190607 #11 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+0x12/0x20 mm/kasan/common.c:614 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131 css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 css_task_iter_start+0x18b/0x230 kernel/cgroup/cgroup.c:4543 mem_cgroup_scan_tasks+0xaf/0x180 mm/memcontrol.c:1167 select_bad_process mm/oom_kill.c:374 [inline] out_of_memory mm/oom_kill.c:1088 [inline] out_of_memory+0x6b2/0x1280 mm/oom_kill.c:1035 mem_cgroup_out_of_memory+0x1ca/0x230 mm/memcontrol.c:1573 mem_cgroup_oom mm/memcontrol.c:1905 [inline] try_charge+0xfbe/0x1480 mm/memcontrol.c:2468 mem_cgroup_try_charge+0x24d/0x5e0 mm/memcontrol.c:6073 mem_cgroup_try_charge_delay+0x1f/0xa0 mm/memcontrol.c:6088 do_anonymous_page mm/memory.c:3036 [inline] handle_pte_fault mm/memory.c:3890 [inline] __handle_mm_fault+0x1e1a/0x3eb0 mm/memory.c:4016 handle_mm_fault+0x3b7/0xa90 mm/memory.c:4053 faultin_page mm/gup.c:654 [inline] __get_user_pages+0x7b6/0x1a40 mm/gup.c:857 populate_vma_page_range+0x20d/0x2a0 mm/gup.c:1560 __mm_populate+0x204/0x380 mm/gup.c:1608 mm_populate include/linux/mm.h:2387 [inline] __do_sys_mlockall mm/mlock.c:819 [inline] __se_sys_mlockall mm/mlock.c:795 [inline] __x64_sys_mlockall+0x373/0x510 mm/mlock.c:795 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459279 Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f0135bd0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000097 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000459279 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0135bd16d4 R13: 00000000004c555e R14: 00000000004d9900 R15: 00000000ffffffff Allocated by task 8550: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:489 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497 slab_post_alloc_hook mm/slab.h:444 [inline] slab_alloc_node mm/slab.c:3263 [inline] kmem_cache_alloc_node+0x131/0x700 mm/slab.c:3573 alloc_task_struct_node kernel/fork.c:160 [inline] dup_task_struct kernel/fork.c:848 [inline] copy_process.part.0+0x42d2/0x6720 kernel/fork.c:1896 copy_process kernel/fork.c:1828 [inline] _do_fork+0x25d/0xfe0 kernel/fork.c:2394 __do_sys_clone kernel/fork.c:2501 [inline] __se_sys_clone kernel/fork.c:2495 [inline] __x64_sys_clone+0xbf/0x150 kernel/fork.c:2495 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 30592: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 __cache_free mm/slab.c:3426 [inline] kmem_cache_free+0x86/0x320 mm/slab.c:3692 free_task_struct kernel/fork.c:165 [inline] free_task+0xdd/0x120 kernel/fork.c:460 __put_task_struct+0x1fd/0x4e0 kernel/fork.c:733 put_task_struct include/linux/sched/task.h:99 [inline] delayed_put_task_struct+0x1ea/0x340 kernel/exit.c:182 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2092 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline] rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291 __do_softirq+0x25c/0x94c kernel/softirq.c:293 The buggy address belongs to the object at ffff888091002340 which belongs to the cache task_struct(17:syz0) of size 6080 The buggy address is located 4444 bytes inside of 6080-byte region [ffff888091002340, ffff888091003b00) The buggy address belongs to the page: page:ffffea0002440080 refcount:1 mapcount:0 mapping:ffff8880694fcdc0 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea0002376e88 ffffea000233a708 ffff8880694fcdc0 raw: 0000000000000000 ffff888091002340 0000000100000001 ffff88809a4fab40 page dumped because: kasan: bad access detected page->mem_cgroup:ffff88809a4fab40 Memory state around the buggy address: ffff888091003380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888091003400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888091003480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888091003500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888091003580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================