From fa2c25b4add57888acfa89e398389e267bff3dcf Mon Sep 17 00:00:00 2001 From: Jia Jia Date: Sun, 30 Aug 2026 10:33:54 +0800 Subject: [PATCH] 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. Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace") Signed-off-by: Jia Jia Signed-off-by: Michael S. Tsirkin Message-ID: <20260830023354.115333-1-physicalmtea@gmail.com> --- drivers/vdpa/vdpa_user/vduse_dev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c index 766789a7bbfa..4dea4d6a3855 100644 --- a/drivers/vdpa/vdpa_user/vduse_dev.c +++ b/drivers/vdpa/vdpa_user/vduse_dev.c @@ -2227,7 +2227,9 @@ static bool vduse_validate_config(struct vduse_dev_config *config, return false; } - if (config->vq_align > PAGE_SIZE) + if (config->vq_align < VRING_USED_ALIGN_SIZE || + !is_power_of_2(config->vq_align) || + config->vq_align > PAGE_SIZE) return false; if (config->config_size > PAGE_SIZE)