Re: WARNING in hwsim_new_radio_nl

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    4f8a3cc1 Merge tag 'x86-urgent-2020-04-12' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110243b3e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3bfbde87e8e65624
dashboard link: https://syzkaller.appspot.com/bug?extid=a4aee3f42d7584d76761
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=100825afe00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10df613fe00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a4aee3f42d7584d76761@xxxxxxxxxxxxxxxxxxxxxxxxx

netlink: 98586 bytes leftover after parsing attributes in process `syz-executor425'.
------------[ cut here ]------------
precision 33020 too large
WARNING: CPU: 1 PID: 6998 at lib/vsprintf.c:2471 set_precision lib/vsprintf.c:2471 [inline]
WARNING: CPU: 1 PID: 6998 at lib/vsprintf.c:2471 vsnprintf+0x1467/0x1aa0 lib/vsprintf.c:2547
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 6998 Comm: syz-executor425 Not tainted 5.6.0-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+0x1e9/0x30e lib/dump_stack.c:118
 panic+0x264/0x7a0 kernel/panic.c:221
 __warn+0x209/0x210 kernel/panic.c:582
 report_bug+0x1ac/0x2d0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 do_error_trap+0xca/0x1c0 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:set_precision lib/vsprintf.c:2471 [inline]
RIP: 0010:vsnprintf+0x1467/0x1aa0 lib/vsprintf.c:2547
Code: a6 bb fd 48 8d 5c 24 48 e9 8e fc ff ff e8 01 a6 bb fd c6 05 bf 06 b0 05 01 48 c7 c7 c1 d3 f2 88 44 89 fe 31 c0 e8 29 ba 8d fd <0f> 0b e9 b7 f6 ff ff e8 dd a5 bb fd c6 05 9a 06 b0 05 01 48 c7 c7
RSP: 0018:ffffc90001647780 EFLAGS: 00010246
RAX: 2f9f2ace1f35b900 RBX: ffffc900016477c8 RCX: ffff88809d86c2c0
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000286
RBP: 80fc0000ffffff02 R08: dffffc0000000000 R09: fffffbfff1628ea5
R10: fffffbfff1628ea5 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff88ea3058 R15: 00000000000080fc
 kvasprintf+0x59/0xf0 lib/kasprintf.c:22
 kasprintf+0x6a/0x90 lib/kasprintf.c:59
 hwsim_new_radio_nl+0x95c/0xf30 drivers/net/wireless/mac80211_hwsim.c:3672
 genl_family_rcv_msg_doit net/netlink/genetlink.c:673 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:718 [inline]
 genl_rcv_msg+0x1054/0x1530 net/netlink/genetlink.c:735
 netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2469
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:746
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x4f9/0x7c0 net/socket.c:2362
 ___sys_sendmsg net/socket.c:2416 [inline]
 __sys_sendmsg+0x2a6/0x360 net/socket.c:2449
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x4401f9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffecc373af8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401f9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a80
R13: 0000000000401b10 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..