================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff88806eb64b24 by task syz-executor.2/15593 CPU: 1 PID: 15593 Comm: syz-executor.2 Not tainted 5.2.0-rc3-next-20190605 #9 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:00007ff0be955c78 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: 00007ff0be9566d4 R13: 00000000004c5325 R14: 00000000004d9418 R15: 00000000ffffffff Allocated by task 15295: 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 pskb_expand_head+0x151/0xe00 net/core/skbuff.c:1527 __skb_cow include/linux/skbuff.h:3034 [inline] skb_cow_head include/linux/skbuff.h:3068 [inline] l2tp_xmit_skb+0xe4e/0x13e0 net/l2tp/l2tp_core.c:1072 pppol2tp_sendmsg+0x4a2/0x6b0 net/l2tp/l2tp_ppp.c:325 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2287 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2389 __do_sys_sendmmsg net/socket.c:2418 [inline] __se_sys_sendmmsg net/socket.c:2415 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2415 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 15295: 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] kfree_skb net/core/skbuff.c:695 [inline] kfree_skb+0xe8/0x390 net/core/skbuff.c:689 l2tp_xmit_skb+0xd57/0x13e0 net/l2tp/l2tp_core.c:1088 pppol2tp_sendmsg+0x4a2/0x6b0 net/l2tp/l2tp_ppp.c:325 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2287 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2389 __do_sys_sendmmsg net/socket.c:2418 [inline] __se_sys_sendmmsg net/socket.c:2415 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2415 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 ffff88806eb64940 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 484 bytes inside of 1024-byte region [ffff88806eb64940, ffff88806eb64d40) The buggy address belongs to the page: page:ffffea0001bad900 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea0002468a88 ffffea00019ebb08 ffff8880aa400ac0 raw: 0000000000000000 ffff88806eb64040 0000000100000007 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88806eb64a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88806eb64a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88806eb64b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88806eb64b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88806eb64c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================