linux-kernel - [syzbot] [net?] KMSAN: uninit-value in __ipv6_dev_mc

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Message-ID: <681e5edb.050a0220.a19a9.013e.GAE@google.com>
Date: Fri, 09 May 2025 13:00:27 -0700
From: syzbot <syzbot+3735d5f00e991698985a@...kaller.appspotmail.com>
To: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com, 
	horms@...nel.org, kuba@...nel.org, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] KMSAN: uninit-value in __ipv6_dev_mc_inc (2)

Hello,

syzbot found the following issue on:

HEAD commit:    02ddfb981de8 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=149d2cf4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9dc42c34a3f5c357
dashboard link: https://syzkaller.appspot.com/bug?extid=3735d5f00e991698985a
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5ca57f5a3f77/disk-02ddfb98.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3f23cbc11e68/vmlinux-02ddfb98.xz
kernel image: https://storage.googleapis.com/syzbot-assets/73e63afac354/bzImage-02ddfb98.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3735d5f00e991698985a@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in __ipv6_dev_mc_inc+0x4f0/0x1640 net/ipv6/mcast.c:966
 __ipv6_dev_mc_inc+0x4f0/0x1640 net/ipv6/mcast.c:966
 ipv6_dev_mc_inc+0x38/0x50 net/ipv6/mcast.c:997
 addrconf_join_solict net/ipv6/addrconf.c:2242 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:4100 [inline]
 addrconf_dad_work+0x401/0x1d10 net/ipv6/addrconf.c:4228
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb97/0x1d90 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd59/0xf00 kernel/kthread.c:464
 ret_from_fork+0x6e/0x90 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Local variable maddr.i.i created at:
 addrconf_join_solict net/ipv6/addrconf.c:2236 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:4100 [inline]
 addrconf_dad_work+0x244/0x1d10 net/ipv6/addrconf.c:4228
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb97/0x1d90 kernel/workqueue.c:3319

CPU: 1 UID: 0 PID: 3845 Comm: kworker/u8:19 Not tainted 6.15.0-rc3-syzkaller-00094-g02ddfb981de8 #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
Workqueue: ipv6_addrconf addrconf_dad_work
=====================================================


---
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