================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff88808c46549c by task syz-executor.0/7831 CPU: 0 PID: 7831 Comm: syz-executor.0 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 pidlist_array_load+0x181/0xa80 kernel/cgroup/cgroup-v1.c:372 cgroup_pidlist_start+0x37e/0x4c0 kernel/cgroup/cgroup-v1.c:442 cgroup_seqfile_start+0xa4/0xd0 kernel/cgroup/cgroup.c:3752 kernfs_seq_start+0xdc/0x190 fs/kernfs/file.c:118 seq_read+0x2a7/0x1110 fs/seq_file.c:224 kernfs_fop_read+0xed/0x560 fs/kernfs/file.c:252 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 do_preadv+0x1c4/0x280 fs/read_write.c:1089 __do_sys_preadv fs/read_write.c:1139 [inline] __se_sys_preadv fs/read_write.c:1134 [inline] __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1134 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:00007f6a2bfbcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459279 RDX: 0000000000000001 RSI: 0000000020000100 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6a2bfbd6d4 R13: 00000000004c6376 R14: 00000000004dae78 R15: 00000000ffffffff Allocated by task 8891: 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 mm/slab.c:3320 [inline] kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3482 anon_vma_chain_alloc mm/rmap.c:129 [inline] anon_vma_clone+0xde/0x480 mm/rmap.c:269 anon_vma_fork+0x8f/0x4a0 mm/rmap.c:332 dup_mmap kernel/fork.c:543 [inline] dup_mm+0x992/0x13b0 kernel/fork.c:1343 copy_mm kernel/fork.c:1399 [inline] copy_process.part.0+0x2baa/0x6720 kernel/fork.c:2057 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 7513: 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 anon_vma_chain_free mm/rmap.c:134 [inline] unlink_anon_vmas+0x2ba/0x870 mm/rmap.c:401 free_pgtables+0xe6/0x2f0 mm/memory.c:381 exit_mmap+0x2bc/0x510 mm/mmap.c:3161 __mmput kernel/fork.c:1061 [inline] mmput+0x15f/0x4c0 kernel/fork.c:1082 exit_mm kernel/exit.c:547 [inline] do_exit+0x816/0x2fa0 kernel/exit.c:864 do_group_exit+0x135/0x360 kernel/exit.c:981 get_signal+0x463/0x2490 kernel/signal.c:2728 do_signal+0x87/0x1990 arch/x86/kernel/signal.c:815 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88808c465460 which belongs to the cache anon_vma_chain(49:syz1) of size 80 The buggy address is located 60 bytes inside of 80-byte region [ffff88808c465460, ffff88808c4654b0) The buggy address belongs to the page: page:ffffea0002311940 refcount:1 mapcount:0 mapping:ffff8880847da1c0 index:0xffff88808c465a10 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0002477b08 ffffea0002744b48 ffff8880847da1c0 raw: ffff88808c465a10 ffff88808c465000 0000000100000014 ffff888064254740 page dumped because: kasan: bad access detected page->mem_cgroup:ffff888064254740 Memory state around the buggy address: ffff88808c465380: fb fb fb fb fb fb fb fb fb fb fc fc fc fc fb fb ffff88808c465400: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb >ffff88808c465480: fb fb fb fb fb fb fc fc fc fc fb fb fb fb fb fb ^ ffff88808c465500: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb ffff88808c465580: fb fb fc fc fc fc fb fb fb fb fb fb fb fb fb fb ==================================================================