Subject: [syzbot] KMSAN: uninit-value in ethnl_set_linkmodes (2)

From: syzbot <[email-masked]>
Date: Mon, 04 Jul 2022 06:27:30 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    4b28366af7d9 x86: kmsan: enable KMSAN builds for x86
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=169d3317f00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d14e10a167d1c585
dashboard link: https://syzkaller.appspot.com/bug?extid=ef6edd9f1baaa54d6235
compiler:       clang version 15.0.0 (https://github.com/llvm/llvm-project.git 610139d2d9ce6746b3c617fb3e2f7886272d26ff), GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

=====================================================
BUG: KMSAN: uninit-value in ethnl_update_u32 net/ethtool/netlink.h:81 [inline]
BUG: KMSAN: uninit-value in ethnl_update_linkmodes net/ethtool/linkmodes.c:295 [inline]
BUG: KMSAN: uninit-value in ethnl_set_linkmodes+0x1469/0x2270 net/ethtool/linkmodes.c:344
 ethnl_update_u32 net/ethtool/netlink.h:81 [inline]
 ethnl_update_linkmodes net/ethtool/linkmodes.c:295 [inline]
 ethnl_set_linkmodes+0x1469/0x2270 net/ethtool/linkmodes.c:344
 genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
 genl_rcv_msg+0x103f/0x1260 net/netlink/genetlink.c:792
 netlink_rcv_skb+0x3a5/0x6c0 net/netlink/af_netlink.c:2501
 genl_rcv+0x3c/0x50 net/netlink/genetlink.c:803
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0xf3b/0x1270 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x1288/0x1440 net/netlink/af_netlink.c:1921
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0xabc/0xe90 net/socket.c:2492
 ___sys_sendmsg+0x2a5/0x350 net/socket.c:2546
 __sys_sendmsg net/socket.c:2575 [inline]
 __do_sys_sendmsg net/socket.c:2584 [inline]
 __se_sys_sendmsg net/socket.c:2582 [inline]
 __x64_sys_sendmsg+0x367/0x540 net/socket.c:2582
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Uninit was stored to memory at:
 tun_get_link_ksettings+0x3e/0x60 drivers/net/tun.c:3515
 __ethtool_get_link_ksettings+0x181/0x270 net/ethtool/ioctl.c:461
 ethnl_set_linkmodes+0x57c/0x2270 net/ethtool/linkmodes.c:338
 genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
 genl_rcv_msg+0x103f/0x1260 net/netlink/genetlink.c:792
 netlink_rcv_skb+0x3a5/0x6c0 net/netlink/af_netlink.c:2501
 genl_rcv+0x3c/0x50 net/netlink/genetlink.c:803
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0xf3b/0x1270 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x1288/0x1440 net/netlink/af_netlink.c:1921
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0xabc/0xe90 net/socket.c:2492
 ___sys_sendmsg+0x2a5/0x350 net/socket.c:2546
 __sys_sendmsg net/socket.c:2575 [inline]
 __do_sys_sendmsg net/socket.c:2584 [inline]
 __se_sys_sendmsg net/socket.c:2582 [inline]
 __x64_sys_sendmsg+0x367/0x540 net/socket.c:2582
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Uninit was stored to memory at:
 tun_set_link_ksettings+0x3e/0x60 drivers/net/tun.c:3524
 ethtool_set_link_ksettings+0x607/0x6a0 net/ethtool/ioctl.c:628
 __dev_ethtool net/ethtool/ioctl.c:2997 [inline]
 dev_ethtool+0x1862/0x2600 net/ethtool/ioctl.c:3051
 dev_ioctl+0x369/0x1020 net/core/dev_ioctl.c:524
 sock_do_ioctl+0x295/0x540 net/socket.c:1183
 sock_ioctl+0x556/0xc90 net/socket.c:1286
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856
 __x64_sys_ioctl+0x92/0xd0 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Local variable link_ksettings created at:
 ethtool_set_link_ksettings+0x54/0x6a0 net/ethtool/ioctl.c:596
 __dev_ethtool net/ethtool/ioctl.c:2997 [inline]
 dev_ethtool+0x1862/0x2600 net/ethtool/ioctl.c:3051

CPU: 0 PID: 20786 Comm: syz-executor.2 Not tainted 5.19.0-rc3-syzkaller-30868-g4b28366af7d9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================

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