[syzbot] [batman?] KMSAN: uninit-value in batadv_mcast_mla_update

[syzbot]

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+1daa6a...@syzkaller.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
=====================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.