KMSAN: uninit-value in eth_type_trans

[Aleksandr Nogikh]

Hello net developers,

I hit the following kernel crash when I try to boot a CONFIG_KMSAN=y kernel on qemu:

KMSAN: uninit-value in eth_type_trans

Could you please have a look?

Kernel: torvalds
Commit: cec1e6e5d1ab33403b809f79cd20d6aff124ccfe
Config: https://raw.githubusercontent.com/google/syzkaller/refs/heads/master/dashboard/config/linux/upstream-kmsan.config

Qemu command to reproduce:

qemu-system-x86_64 -m 8G -smp 2,sockets=2,cores=1 -machine pc-q35-10.0 \
-enable-kvm -display none -serial stdio -snapshot \
-device virtio-blk-pci,drive=myhd -drive file=~/buildroot_amd64_2024.09,format=raw,if=none,id=myhd \
-kernel ~/linux/arch/x86/boot/bzImage -append "root=/dev/vda1" -cpu max \
-net nic,model=e1000 -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10021-:22

The command used the buildroot image below:
$ wget 'https://storage.googleapis.com/syzkaller/images/buildroot_amd64_2024.09.gz'
$ gunzip buildroot_amd64_2024.09.gz

Full symbolized report:

BUG: KMSAN: uninit-value in eth_skb_pkt_type include/linux/etherdevice.h:627 [inline]
BUG: KMSAN: uninit-value in eth_type_trans+0x4ee/0x980 net/ethernet/eth.c:165
eth_skb_pkt_type include/linux/etherdevice.h:627 [inline]
eth_type_trans+0x4ee/0x980 net/ethernet/eth.c:165
e1000_receive_skb drivers/net/ethernet/intel/e1000/e1000_main.c:4005 [inline]
e1000_clean_rx_irq+0x1256/0x1cf0 drivers/net/ethernet/intel/e1000/e1000_main.c:4465
e1000_clean+0x1e4b/0x5f10 drivers/net/ethernet/intel/e1000/e1000_main.c:3807
__napi_poll+0xda/0x850 net/core/dev.c:7506
napi_poll net/core/dev.c:7569 [inline]
net_rx_action+0xa56/0x1b00 net/core/dev.c:7696
handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x66/0x180 kernel/softirq.c:680
irq_exit_rcu+0x12/0x20 kernel/softirq.c:696
common_interrupt+0x99/0xb0 arch/x86/kernel/irq.c:318
asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:693
native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
pv_native_safe_halt+0x17/0x20 arch/x86/kernel/paravirt.c:81
arch_safe_halt arch/x86/kernel/process.c:756 [inline]
default_idle+0xd/0x20 arch/x86/kernel/process.c:757
arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:794
default_idle_call+0x41/0x70 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0x1dc/0x790 kernel/sched/idle.c:330
cpu_startup_entry+0x60/0x80 kernel/sched/idle.c:428
rest_init+0x1df/0x260 init/main.c:744
start_kernel+0x76e/0x960 init/main.c:1097
x86_64_start_reservations+0x28/0x30 arch/x86/kernel/head64.c:307
x86_64_start_kernel+0x139/0x140 arch/x86/kernel/head64.c:288
common_startup_64+0x13e/0x147

Uninit was stored to memory at:
skb_put_data include/linux/skbuff.h:2753 [inline]
e1000_copybreak drivers/net/ethernet/intel/e1000/e1000_main.c:4339 [inline]
e1000_clean_rx_irq+0x870/0x1cf0 drivers/net/ethernet/intel/e1000/e1000_main.c:4384
e1000_clean+0x1e4b/0x5f10 drivers/net/ethernet/intel/e1000/e1000_main.c:3807
__napi_poll+0xda/0x850 net/core/dev.c:7506
napi_poll net/core/dev.c:7569 [inline]
net_rx_action+0xa56/0x1b00 net/core/dev.c:7696
handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x66/0x180 kernel/softirq.c:680
irq_exit_rcu+0x12/0x20 kernel/softirq.c:696
common_interrupt+0x99/0xb0 arch/x86/kernel/irq.c:318
asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:693

Uninit was stored to memory at:
swiotlb_bounce+0x470/0x640 kernel/dma/swiotlb.c:-1
__swiotlb_sync_single_for_cpu+0x9e/0xc0 kernel/dma/swiotlb.c:1567
swiotlb_sync_single_for_cpu include/linux/swiotlb.h:279 [inline]
dma_direct_sync_single_for_cpu kernel/dma/direct.h:77 [inline]
__dma_sync_single_for_cpu+0x50d/0x710 kernel/dma/mapping.c:370
dma_sync_single_for_cpu include/linux/dma-mapping.h:381 [inline]
e1000_copybreak drivers/net/ethernet/intel/e1000/e1000_main.c:4336 [inline]
e1000_clean_rx_irq+0x7dc/0x1cf0 drivers/net/ethernet/intel/e1000/e1000_main.c:4384
e1000_clean+0x1e4b/0x5f10 drivers/net/ethernet/intel/e1000/e1000_main.c:3807
__napi_poll+0xda/0x850 net/core/dev.c:7506
napi_poll net/core/dev.c:7569 [inline]
net_rx_action+0xa56/0x1b00 net/core/dev.c:7696
handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x66/0x180 kernel/softirq.c:680
irq_exit_rcu+0x12/0x20 kernel/softirq.c:696
common_interrupt+0x99/0xb0 arch/x86/kernel/irq.c:318
asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:693

Uninit was stored to memory at:
swiotlb_bounce+0x470/0x640 kernel/dma/swiotlb.c:-1
swiotlb_tbl_map_single+0x2956/0x2b20 kernel/dma/swiotlb.c:1439
swiotlb_map+0x349/0x1050 kernel/dma/swiotlb.c:1584
dma_direct_map_page kernel/dma/direct.h:-1 [inline]
dma_map_page_attrs+0x614/0xef0 kernel/dma/mapping.c:169
dma_map_single_attrs include/linux/dma-mapping.h:469 [inline]
e1000_alloc_rx_buffers+0x96d/0x1600 drivers/net/ethernet/intel/e1000/e1000_main.c:4616
e1000_configure+0x16fe/0x1930 drivers/net/ethernet/intel/e1000/e1000_main.c:377
e1000_open+0x985/0x14d0 drivers/net/ethernet/intel/e1000/e1000_main.c:1388
__dev_open+0x7c2/0xc40 net/core/dev.c:1682
__dev_change_flags+0x3ae/0x9b0 net/core/dev.c:9549
netif_change_flags+0x8d/0x1e0 net/core/dev.c:9612
dev_change_flags+0x18c/0x320 net/core/dev_api.c:68
devinet_ioctl+0x162d/0x2570 net/ipv4/devinet.c:1199
inet_ioctl+0x4c0/0x6f0 net/ipv4/af_inet.c:1001
sock_do_ioctl+0x9f/0x480 net/socket.c:1238
sock_ioctl+0x70b/0xd60 net/socket.c:1359
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0x23c/0x400 fs/ioctl.c:584
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:584
x64_sys_call+0x1cbc/0x3e20 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
__alloc_frozen_pages_noprof+0x648/0xe80 mm/page_alloc.c:5171
__alloc_pages_noprof+0x41/0xd0 mm/page_alloc.c:5182
__page_frag_cache_refill+0x57/0x2a0 mm/page_frag_cache.c:59
__page_frag_alloc_align+0xd0/0x690 mm/page_frag_cache.c:103
__napi_alloc_frag_align net/core/skbuff.c:248 [inline]
__netdev_alloc_frag_align+0x1b7/0x1f0 net/core/skbuff.c:269
netdev_alloc_frag include/linux/skbuff.h:3408 [inline]
e1000_alloc_frag drivers/net/ethernet/intel/e1000/e1000_main.c:2074 [inline]
e1000_alloc_rx_buffers+0x276/0x1600 drivers/net/ethernet/intel/e1000/e1000_main.c:4584
e1000_configure+0x16fe/0x1930 drivers/net/ethernet/intel/e1000/e1000_main.c:377
e1000_open+0x985/0x14d0 drivers/net/ethernet/intel/e1000/e1000_main.c:1388
__dev_open+0x7c2/0xc40 net/core/dev.c:1682
__dev_change_flags+0x3ae/0x9b0 net/core/dev.c:9549
netif_change_flags+0x8d/0x1e0 net/core/dev.c:9612
dev_change_flags+0x18c/0x320 net/core/dev_api.c:68
devinet_ioctl+0x162d/0x2570 net/ipv4/devinet.c:1199
inet_ioctl+0x4c0/0x6f0 net/ipv4/af_inet.c:1001
sock_do_ioctl+0x9f/0x480 net/socket.c:1238
sock_ioctl+0x70b/0xd60 net/socket.c:1359
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0x23c/0x400 fs/ioctl.c:584
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:584
x64_sys_call+0x1cbc/0x3e20 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f


--
Aleksandr

[Alexander Potapenko]

On Fri, Sep 26, 2025 at 12:36 AM Aleksandr Nogikh <nog...@google.com> wrote:
>
> Hello net developers,

CCing DMA developers, as this seems to be a generic problem.
See the question below, after the KMSAN report.

Folks, as far as I understand, dma_direct_sync_single_for_cpu() and
dma_direct_sync_single_for_device() are the places where we send data
to or from the device.
Should we add KMSAN annotations to those functions to catch infoleaks
and mark data from devices as initialized?