================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff8880982e621c by task syz-executor.2/18508 CPU: 1 PID: 18508 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 do_user_addr_fault arch/x86/mm/fault.c:1455 [inline] __do_page_fault+0x5ef/0xda0 arch/x86/mm/fault.c:1521 do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1552 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156 RIP: 0033:0x410bbf Code: 0f 84 c8 02 00 00 48 83 bd 78 ff ff ff 00 0f 84 f9 04 00 00 48 8b 95 68 ff ff ff 44 89 95 38 ff ff ff 4c 8d ac 10 00 f7 ff ff <49> 89 85 90 06 00 00 49 8d 85 10 03 00 00 49 89 95 98 06 00 00 41 RSP: 002b:00007ffdc28b75c0 EFLAGS: 00010206 RAX: 00007fa88331b000 RBX: 0000000000020000 RCX: 00000000004592ca RDX: 0000000000021000 RSI: 0000000000021000 RDI: 0000000000000000 RBP: 00007ffdc28b76a0 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdc28b7790 R13: 00007fa88333b700 R14: 0000000000000000 R15: 000000000075bf2c Allocated by task 9027: 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_kmalloc+0x9/0x10 mm/kasan/common.c:503 __do_kmalloc_node mm/slab.c:3614 [inline] __kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3628 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:139 __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:207 alloc_skb include/linux/skbuff.h:1054 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1179 [inline] netlink_sendmsg+0x972/0xd60 net/netlink/af_netlink.c:1897 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 ___sys_sendmsg+0x803/0x920 net/socket.c:2287 __sys_sendmsg+0x105/0x1d0 net/socket.c:2332 __do_sys_sendmsg net/socket.c:2341 [inline] __se_sys_sendmsg net/socket.c:2339 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2339 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9027: 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] kfree+0x106/0x2a0 mm/slab.c:3753 skb_free_head+0x93/0xb0 net/core/skbuff.c:589 skb_release_data+0x42d/0x7c0 net/core/skbuff.c:609 skb_release_all+0x4d/0x60 net/core/skbuff.c:663 __kfree_skb net/core/skbuff.c:677 [inline] consume_skb net/core/skbuff.c:737 [inline] consume_skb+0xe2/0x380 net/core/skbuff.c:731 netlink_unicast_kernel net/netlink/af_netlink.c:1308 [inline] netlink_unicast+0x539/0x710 net/netlink/af_netlink.c:1333 netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1922 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 ___sys_sendmsg+0x803/0x920 net/socket.c:2287 __sys_sendmsg+0x105/0x1d0 net/socket.c:2332 __do_sys_sendmsg net/socket.c:2341 [inline] __se_sys_sendmsg net/socket.c:2339 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2339 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880982e6040 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 476 bytes inside of 1024-byte region [ffff8880982e6040, ffff8880982e6440) The buggy address belongs to the page: page:ffffea000260b980 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff8880982e6040 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea00028e9e88 ffffea0002835b08 ffff8880aa400ac0 raw: ffff8880982e6040 ffff8880982e6040 0000000100000005 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880982e6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880982e6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880982e6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880982e6280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880982e6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================