Hello, syzbot found the following crash on: HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=120f87e5100000 kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 dashboard link: https://syzkaller.appspot.com/bug?extid=14e0e4960091ffae7cf7 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11818aa7100000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10f997d3100000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+14e0e4960091ffae7cf7@xxxxxxxxxxxxxxxxxxxxxxxxx netlink: 26 bytes leftover after parsing attributes in process `syz-executor982'. ================================================================== BUG: KASAN: use-after-free in nla_len include/net/netlink.h:1135 [inline] BUG: KASAN: use-after-free in nla_memcpy+0x9c/0xa0 lib/nlattr.c:724 Read of size 2 at addr ffff8880a0ca8414 by task syz-executor982/6816 CPU: 0 PID: 6816 Comm: syz-executor982 Not tainted 5.8.0-rc2-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+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 nla_len include/net/netlink.h:1135 [inline] nla_memcpy+0x9c/0xa0 lib/nlattr.c:724 nla_get_u64 include/net/netlink.h:1606 [inline] __cfg802154_wpan_dev_from_attrs+0x3e0/0x510 net/ieee802154/nl802154.c:55 nl802154_prepare_wpan_dev_dump.constprop.0+0xf9/0x490 net/ieee802154/nl802154.c:245 nl802154_dump_llsec_dev+0xc0/0xb10 net/ieee802154/nl802154.c:1655 genl_lock_dumpit+0x7f/0xb0 net/netlink/genetlink.c:575 netlink_dump+0x4cd/0xf60 net/netlink/af_netlink.c:2245 __netlink_dump_start+0x643/0x900 net/netlink/af_netlink.c:2353 genl_family_rcv_msg_dumpit+0x2ac/0x310 net/netlink/genetlink.c:638 genl_family_rcv_msg net/netlink/genetlink.c:733 [inline] genl_rcv_msg+0x797/0x9e0 net/netlink/genetlink.c:753 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2469 genl_rcv+0x24/0x40 net/netlink/genetlink.c:764 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4413c9 Code: Bad RIP value. RSP: 002b:00007fff5b30bca8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004413c9 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 00000000006cb018 R08: 00000000004002c8 R09: 00000000004002c8 R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000402140 R13: 00000000004021d0 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 6815: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0xae/0x550 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1083 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline] netlink_sendmsg+0x94f/0xd90 net/netlink/af_netlink.c:1893 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 6815: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x103/0x2c0 mm/slab.c:3757 skb_free_head net/core/skbuff.c:590 [inline] skb_release_data+0x6d9/0x910 net/core/skbuff.c:610 skb_release_all net/core/skbuff.c:664 [inline] __kfree_skb net/core/skbuff.c:678 [inline] consume_skb net/core/skbuff.c:837 [inline] consume_skb+0xc2/0x160 net/core/skbuff.c:831 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x53b/0x7d0 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff8880a0ca8400 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 20 bytes inside of 512-byte region [ffff8880a0ca8400, ffff8880a0ca8600) The buggy address belongs to the page: page:ffffea0002832a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00029e1288 ffffea00028ef888 ffff8880aa000a80 raw: 0000000000000000 ffff8880a0ca8000 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a0ca8300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a0ca8380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880a0ca8400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a0ca8480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a0ca8500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches
