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

[syzbot <syzbot+f13c19f75e1097abd116@syzkaller.appspotmail.com>]

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+f13c19f75e1097abd116@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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