CVE-2026-97989vduse: validate virtqueue alignment

Official description

In the Linux kernel, the following vulnerability has been resolved: vduse: validate virtqueue alignment vduse_validate_config() only checks the upper bound of vq_align. Invalid values can therefore reach vring_create_virtqueue_map(). The split-ring helpers use align - 1 as a bit mask, so the alignment must be a non-zero power of two. A zero value makes vring_size() drop the descriptor and available-ring part and vring_init() leave the used ring pointer NULL. The VIRTIO spec requires the used ring to start at an address aligned to at least 4 bytes. Reject values below VRING_USED_ALIGN_SIZE as well as non-power-of-two values before they reach the virtio ring helpers. Opening a virtio-net device created with vq_align=0 triggered: BUG: KASAN: null-ptr-deref in virtqueue_kick_prepare_split+0xe3/0x100 Read of size 2 at addr 0000000000000000 by task systemd-network/1062 Call Trace (relevant frames): dump_stack_lvl print_report kasan_report __asan_load2 virtqueue_kick_prepare_split+0xe3/0x100 virtqueue_kick_prepare+0x40/0x60 try_fill_recv+0x857/0x1250 virtnet_open+0x189/0x460 __dev_open+0x225/0x390 __dev_change_flags+0x368/0x3b0 netif_change_flags+0x56/0xc0 do_setlink.isra.0+0x68c/0x1e30 Validate the value before it reaches the virtio ring helpers.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/650bac9c73d3b4d83be683028283654c05346556
• https://git.kernel.org/stable/c/5d4bdca17d87c90b1d888f8846a781a18aa453c9
• https://git.kernel.org/stable/c/831dab9b9bcc184adf78f18b5b788316e3174aec
• https://git.kernel.org/stable/c/c3c3b0839a1197530cc18f535062fc84dbdfc885
• https://git.kernel.org/stable/c/fa2c25b4add57888acfa89e398389e267bff3dcf