[syzbot] [wpan?] KMSAN: uninit-value in lowpan_xmit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e8c2f9fdadee Merge tag 'for-7.1/hpfs-fixes' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10883b06580000
kernel config: https://syzkaller.appspot.com/x/.config?x=91978e795dcd971b
dashboard link: https://syzkaller.appspot.com/bug?extid=f13c19f75e1097abd116
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6d28568f6ffa/disk-e8c2f9fd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/68a9eec5e7f1/vmlinux-e8c2f9fd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e6a7381a5e55/bzImage-e8c2f9fd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f13c19...@syzkaller.appspotmail.com

dev_queue_xmit include/linux/netdevice.h:3418 [inline]
tx+0xb6/0x440 drivers/block/aoe/aoenet.c:62
kthread+0x17d/0x370 drivers/block/aoe/aoecmd.c:1241
kthread+0x53a/0x5f0 kernel/kthread.c:436
ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
---[ end trace 0000000000000000 ]---
=====================================================
BUG: KMSAN: uninit-value in lowpan_header net/ieee802154/6lowpan/tx.c:240 [inline]
BUG: KMSAN: uninit-value in lowpan_xmit+0xa6b/0x1d00 net/ieee802154/6lowpan/tx.c:282
lowpan_header net/ieee802154/6lowpan/tx.c:240 [inline]
lowpan_xmit+0xa6b/0x1d00 net/ieee802154/6lowpan/tx.c:282
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x22f/0xa80 net/core/dev.c:3904
__dev_queue_xmit+0x2990/0x5a00 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
tx+0xb6/0x440 drivers/block/aoe/aoenet.c:62
kthread+0x17d/0x370 drivers/block/aoe/aoecmd.c:1241
kthread+0x53a/0x5f0 kernel/kthread.c:436
ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was stored to memory at:
lowpan_header net/ieee802154/6lowpan/tx.c:231 [inline]
lowpan_xmit+0x68f/0x1d00 net/ieee802154/6lowpan/tx.c:282
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x22f/0xa80 net/core/dev.c:3904
__dev_queue_xmit+0x2990/0x5a00 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
tx+0xb6/0x440 drivers/block/aoe/aoenet.c:62
kthread+0x17d/0x370 drivers/block/aoe/aoecmd.c:1241
kthread+0x53a/0x5f0 kernel/kthread.c:436
ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4577 [inline]
slab_alloc_node mm/slub.c:4899 [inline]
kmem_cache_alloc_node_noprof+0x3cd/0x12c0 mm/slub.c:4951
kmalloc_reserve net/core/skbuff.c:613 [inline]
__alloc_skb+0x855/0x1190 net/core/skbuff.c:713
alloc_skb include/linux/skbuff.h:1383 [inline]
new_skb+0x4a/0x550 drivers/block/aoe/aoecmd.c:66
aoecmd_cfg_pkts drivers/block/aoe/aoecmd.c:430 [inline]
aoecmd_cfg+0x2c2/0xb70 drivers/block/aoe/aoecmd.c:1374
discover_timer+0x64/0x80 drivers/block/aoe/aoemain.c:25
call_timer_fn+0x4c/0x510 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x80a/0xdb0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0x3a/0x70 kernel/time/timer.c:2405
handle_softirqs+0x171/0x7b0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x9a/0x1e0 kernel/softirq.c:735
irq_exit_rcu+0x12/0x20 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0x84/0x90 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:697

CPU: 0 UID: 0 PID: 1310 Comm: aoe_tx0 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
=====================================================


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