================================================================== BUG: KASAN: use-after-free in vlan_dev_get_iflink+0x5f/0x70 net/8021q/vlan_dev.c:767 Read of size 4 at addr ffff88804e8f2100 by task syz-executor.5/19181 CPU: 1 PID: 19181 Comm: syz-executor.5 Not tainted 5.9.0-rc6-next-20200923-syzkaller #0 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+0x198/0x1fb lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:385 __kasan_report mm/kasan/report.c:545 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562 vlan_dev_get_iflink+0x5f/0x70 net/8021q/vlan_dev.c:767 dev_get_iflink+0x73/0xe0 net/core/dev.c:816 rfc2863_policy+0x243/0x2e0 net/core/link_watch.c:41 linkwatch_do_dev+0x2a/0x180 net/core/link_watch.c:160 linkwatch_forget_dev+0x16a/0x200 net/core/link_watch.c:237 netdev_wait_allrefs net/core/dev.c:10043 [inline] netdev_run_todo+0x258/0xb90 net/core/dev.c:10145 rtnl_unlock net/core/rtnetlink.c:112 [inline] rtnetlink_rcv_msg+0x45b/0xad0 net/core/rtnetlink.c:5564 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:671 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2362 ___sys_sendmsg+0xf3/0x170 net/socket.c:2416 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2449 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e179 Code: 3d b2 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 0b b2 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff923ca4c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000002cf40 RCX: 000000000045e179 RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000003 RBP: 000000000118d028 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cff4 R13: 00007ffdbe39f09f R14: 00007ff923ca59c0 R15: 000000000118cff4 Allocated by task 19164: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 kmalloc_node include/linux/slab.h:577 [inline] kvmalloc_node+0x61/0xf0 mm/util.c:575 kvmalloc include/linux/mm.h:765 [inline] kvzalloc include/linux/mm.h:773 [inline] alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:10309 rtnl_create_link+0x219/0xad0 net/core/rtnetlink.c:3169 __rtnl_newlink+0xf9b/0x1750 net/core/rtnetlink.c:3431 rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3500 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:671 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2362 ___sys_sendmsg+0xf3/0x170 net/socket.c:2416 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2449 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 19164: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422 __cache_free mm/slab.c:3416 [inline] kfree+0x10e/0x2a0 mm/slab.c:3754 kvfree+0x42/0x50 mm/util.c:604 device_release+0x9f/0x240 drivers/base/core.c:1799 kobject_cleanup lib/kobject.c:705 [inline] kobject_release lib/kobject.c:736 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x171/0x270 lib/kobject.c:753 netdev_run_todo+0x7a9/0xb90 net/core/dev.c:10168 rtnl_unlock net/core/rtnetlink.c:112 [inline] rtnetlink_rcv_msg+0x45b/0xad0 net/core/rtnetlink.c:5564 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:671 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2362 ___sys_sendmsg+0xf3/0x170 net/socket.c:2416 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2449 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff88804e8f2000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 256 bytes inside of 4096-byte region [ffff88804e8f2000, ffff88804e8f3000) The buggy address belongs to the page: page:0000000072c19dd9 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4e8f2 head:0000000072c19dd9 order:1 compound_mapcount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea000257b088 ffffea00013de488 ffff8880aa040900 raw: 0000000000000000 ffff88804e8f2000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88804e8f2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804e8f2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88804e8f2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88804e8f2180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804e8f2200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================