CVE-2025-38048 virtio_ring: Fix data race by tagging event_triggered as racy for KCSAN
A data race in the Linux kernel's virtio_ring driver can cause temporary notification delays, potentially leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38048?
CVE-2025-38048 is a medium-severity vulnerability in Debian Debian Linux, published on 18 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
virtio_ring: Fix data race by tagging event_triggered as racy for KCSAN
syzbot reports a data-race when accessing the event_triggered, here is the simplified stack when the issue occurred:
================================================================== BUG: KCSAN: data-race in virtqueue_disable_cb / virtqueue_enable_cb_delayed
write to 0xffff8881025bc452 of 1 bytes by task 3288 on cpu 0: virtqueue_enable_cb_delayed+0x42/0x3c0 drivers/virtio/virtio_ring.c:2653 start_xmit+0x230/0x1310 drivers/net/virtio_net.c:3264 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3800 [inline]
read to 0xffff8881025bc452 of 1 bytes by interrupt on cpu 1: virtqueue_disable_cb_split drivers/virtio/virtio_ring.c:880 [inline] virtqueue_disable_cb+0x92/0x180 drivers/virtio/virtio_ring.c:2566 skb_xmit_done+0x5f/0x140 drivers/net/virtio_net.c:777 vring_interrupt+0x161/0x190 drivers/virtio/virtio_ring.c:2715 __handle_irq_event_percpu+0x95/0x490 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
value changed: 0x01 -> 0x00 ==================================================================
When the data race occurs, the function virtqueue_enable_cb_delayed() sets event_triggered to false, and virtqueue_disable_cb_split/packed() reads it as false due to the race condition. Since event_triggered is an unreliable hint used for optimization, this should only cause the driver temporarily suggest that the device not send an interrupt notification when the event index is used.
Fix this KCSAN reported data-race issue by explicitly tagging the access as data_racy.
Weakness: CWE-362
Which versions are affected by CVE-2025-38048?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38048?
Apply the vendor's patch.
Is CVE-2025-38048 being exploited?
There is no known exploitation of CVE-2025-38048 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-38048, DEBIAN-CVE-2025-38048, GHSA-3mg3-84hp-h85m, ROOT-OS-DEBIAN-11-CVE-2025-38048, ROOT-OS-DEBIAN-12-CVE-2025-38048, ROOT-OS-UBUNTU-2204-CVE-2025-38048 and 2 more.