[syzbot] KMSAN: uninit-value in __hw_addr_add_ex

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    81c325bbf94e kmsan: hooks: do not check memory in kmsan_in..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=153cd3c7b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2d8b9a11641dc9aa
dashboard link: https://syzkaller.appspot.com/bug?extid=cec7816c907e0923fdcc
compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

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: syzbot+cec7816c907e0923fdcc@xxxxxxxxxxxxxxxxxxxxxxxxx

IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready
=====================================================
BUG: KMSAN: uninit-value in memcmp+0x23e/0x290 lib/string.c:789
 memcmp+0x23e/0x290 lib/string.c:789
 __hw_addr_add_ex+0x2f9/0x1020 net/core/dev_addr_lists.c:62
 __hw_addr_sync_one net/core/dev_addr_lists.c:210 [inline]
 __hw_addr_sync_multiple+0x35f/0xa40 net/core/dev_addr_lists.c:250
 dev_mc_sync_multiple+0x195/0x2b0 net/core/dev_addr_lists.c:959
 team_set_rx_mode+0x143/0x230 drivers/net/team/team.c:1780
 __dev_set_rx_mode+0x3b0/0x440 net/core/dev.c:8717
 __dev_mc_add net/core/dev_addr_lists.c:836 [inline]
 dev_mc_add+0x180/0x1d0 net/core/dev_addr_lists.c:850
 igmp6_group_added+0x320/0x830 net/ipv6/mcast.c:680
 __ipv6_dev_mc_inc+0x11e9/0x1620 net/ipv6/mcast.c:949
 ipv6_dev_mc_inc+0x70/0x80 net/ipv6/mcast.c:957
 addrconf_join_solict net/ipv6/addrconf.c:2179 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:3958 [inline]
 addrconf_dad_work+0x736/0x2210 net/ipv6/addrconf.c:4085
 process_one_work+0xdb9/0x1820 kernel/workqueue.c:2298
 worker_thread+0x10bc/0x21f0 kernel/workqueue.c:2445
 kthread+0x721/0x850 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

Uninit was stored to memory at:
 __hw_addr_create net/core/dev_addr_lists.c:32 [inline]
 __hw_addr_add_ex+0x718/0x1020 net/core/dev_addr_lists.c:93
 __dev_mc_add net/core/dev_addr_lists.c:832 [inline]
 dev_mc_add+0x10a/0x1d0 net/core/dev_addr_lists.c:850
 igmp6_group_added+0x320/0x830 net/ipv6/mcast.c:680
 __ipv6_dev_mc_inc+0x11e9/0x1620 net/ipv6/mcast.c:949
 ipv6_dev_mc_inc+0x70/0x80 net/ipv6/mcast.c:957
 addrconf_join_solict net/ipv6/addrconf.c:2179 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:3958 [inline]
 addrconf_dad_work+0x736/0x2210 net/ipv6/addrconf.c:4085
 process_one_work+0xdb9/0x1820 kernel/workqueue.c:2298
 worker_thread+0x10bc/0x21f0 kernel/workqueue.c:2445
 kthread+0x721/0x850 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

Local variable buf created at:
 igmp6_group_added+0x9b/0x830 net/ipv6/mcast.c:671
 __ipv6_dev_mc_inc+0x11e9/0x1620 net/ipv6/mcast.c:949

CPU: 1 PID: 25 Comm: kworker/1:1 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_dad_work
=====================================================


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