================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff88809a79cb1c by task syz-executor.3/1354 CPU: 0 PID: 1354 Comm: syz-executor.3 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 __cgroup_procs_start.isra.0+0x32f/0x400 kernel/cgroup/cgroup.c:4638 cgroup_threads_start+0x23/0x30 kernel/cgroup/cgroup.c:4745 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_readv+0x15b/0x330 fs/read_write.c:1034 __do_sys_readv fs/read_write.c:1125 [inline] __se_sys_readv fs/read_write.c:1122 [inline] __x64_sys_readv+0x75/0xb0 fs/read_write.c:1122 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:00007fa648c6cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000013 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279 RDX: 000000000000018f RSI: 00000000200002c0 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa648c6d6d4 R13: 00000000004c6392 R14: 00000000004db1c0 R15: 00000000ffffffff Allocated by task 8848: 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_fclone include/linux/skbuff.h:1104 [inline] sk_stream_alloc_skb+0x2d2/0xc50 net/ipv4/tcp.c:870 tcp_sendmsg_locked+0xc85/0x3920 net/ipv4/tcp.c:1257 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1415 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 sock_write_iter+0x27c/0x3e0 net/socket.c:994 call_write_iter include/linux/fs.h:1870 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 8863: 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 __dev_kfree_skb_any+0xa4/0xd0 net/core/dev.c:2823 dev_consume_skb_any include/linux/netdevice.h:3611 [inline] napi_consume_skb+0x3e8/0x550 net/core/skbuff.c:801 free_old_xmit_skbs+0xee/0x250 drivers/net/virtio_net.c:1366 start_xmit+0x122/0x15a0 drivers/net/virtio_net.c:1562 __netdev_start_xmit include/linux/netdevice.h:4406 [inline] netdev_start_xmit include/linux/netdevice.h:4420 [inline] xmit_one net/core/dev.c:3288 [inline] dev_hard_start_xmit+0x18a/0x950 net/core/dev.c:3304 sch_direct_xmit+0x372/0xc30 net/sched/sch_generic.c:308 __dev_xmit_skb net/core/dev.c:3485 [inline] __dev_queue_xmit+0x27c5/0x36b0 net/core/dev.c:3846 dev_queue_xmit+0x18/0x20 net/core/dev.c:3910 neigh_hh_output include/net/neighbour.h:500 [inline] neigh_output include/net/neighbour.h:509 [inline] ip_finish_output2+0x168a/0x24c0 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:308 [inline] __ip_finish_output+0x5fc/0xbc0 net/ipv4/ip_output.c:290 ip_finish_output+0x38/0x1f0 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip_output+0x21f/0x670 net/ipv4/ip_output.c:415 dst_output include/net/dst.h:433 [inline] ip_local_out+0xbb/0x1b0 net/ipv4/ip_output.c:125 __ip_queue_xmit+0x86f/0x1bf0 net/ipv4/ip_output.c:515 ip_queue_xmit+0x5a/0x70 include/net/ip.h:236 __tcp_transmit_skb+0x1a1a/0x3730 net/ipv4/tcp_output.c:1156 tcp_transmit_skb net/ipv4/tcp_output.c:1172 [inline] tcp_write_xmit+0xe3d/0x57c0 net/ipv4/tcp_output.c:2397 __tcp_push_pending_frames+0xb4/0x350 net/ipv4/tcp_output.c:2573 tcp_push+0x4cd/0x6c0 net/ipv4/tcp.c:719 tcp_sendmsg_locked+0x27bb/0x3920 net/ipv4/tcp.c:1377 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1415 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 sock_write_iter+0x27c/0x3e0 net/socket.c:994 call_write_iter include/linux/fs.h:1870 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 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 ffff88809a79c940 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 476 bytes inside of 1024-byte region [ffff88809a79c940, ffff88809a79cd40) The buggy address belongs to the page: page:ffffea000269e700 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff88809a79c940 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea00028c1b88 ffffea0002361f08 ffff8880aa400ac0 raw: ffff88809a79c940 ffff88809a79c040 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809a79ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809a79ca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88809a79cb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809a79cb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809a79cc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================