linux-kernel - [syzbot] [batman?] KMSAN: uninit-value in batadv_mcast_mla

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <6862c45c.a70a0220.3b7e22.10aa.GAE@google.com>
Date: Mon, 30 Jun 2025 10:07:40 -0700
From: syzbot <syzbot+1daa6a8aecb922ad3c30@...kaller.appspotmail.com>
To: antonio@...delbit.com, b.a.t.m.a.n@...ts.open-mesh.org, 
	davem@...emloft.net, edumazet@...gle.com, horms@...nel.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, marek.lindner@...lbox.org, 
	netdev@...r.kernel.org, pabeni@...hat.com, sven@...fation.org, 
	sw@...onwunderlich.de, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [batman?] KMSAN: uninit-value in batadv_mcast_mla_update

Hello,

syzbot found the following issue on:

HEAD commit:    ee88bddf7f2f Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12b1db70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=595d344ff0b23ac5
dashboard link: https://syzkaller.appspot.com/bug?extid=1daa6a8aecb922ad3c30
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/405f6113ec86/disk-ee88bddf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/57f4fa239393/vmlinux-ee88bddf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/32892fe29e1c/bzImage-ee88bddf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1daa6a8aecb922ad3c30@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in batadv_mcast_mla_is_duplicate net/batman-adv/multicast.c:347 [inline]
BUG: KMSAN: uninit-value in batadv_mcast_mla_tt_retract net/batman-adv/multicast.c:692 [inline]
BUG: KMSAN: uninit-value in __batadv_mcast_mla_update net/batman-adv/multicast.c:920 [inline]
BUG: KMSAN: uninit-value in batadv_mcast_mla_update+0x35f4/0x4f80 net/batman-adv/multicast.c:948
 batadv_mcast_mla_is_duplicate net/batman-adv/multicast.c:347 [inline]
 batadv_mcast_mla_tt_retract net/batman-adv/multicast.c:692 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:920 [inline]
 batadv_mcast_mla_update+0x35f4/0x4f80 net/batman-adv/multicast.c:948
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
 kthread+0xd5c/0xf00 kernel/kthread.c:464
 ret_from_fork+0x1e3/0x310 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __kmalloc_cache_noprof+0x7f7/0xed0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 batadv_mcast_mla_meshif_get_ipv6 net/batman-adv/multicast.c:477 [inline]
 batadv_mcast_mla_meshif_get net/batman-adv/multicast.c:535 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:911 [inline]
 batadv_mcast_mla_update+0x1c17/0x4f80 net/batman-adv/multicast.c:948
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
 kthread+0xd5c/0xf00 kernel/kthread.c:464
 ret_from_fork+0x1e3/0x310 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 1 UID: 0 PID: 68 Comm: kworker/u8:4 Tainted: G        W           6.16.0-rc3-syzkaller-00072-gee88bddf7f2f #0 PREEMPT(undef) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: bat_events batadv_mcast_mla_update
=====================================================


---
This report 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@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup