| From 882f908778da7570332f89b0e64a8905924440fe Mon Sep 17 00:00:00 2001 | |
| From: Sasha Levin <sashal@kernel.org> | |
| Date: Sun, 30 Aug 2026 10:33:54 +0800 | |
| Subject: vduse: validate virtqueue alignment | |
| From: Jia Jia <physicalmtea@gmail.com> | |
| [ Upstream commit fa2c25b4add57888acfa89e398389e267bff3dcf ] | |
| 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 <physicalmtea@gmail.com> | |
| Signed-off-by: Michael S. Tsirkin <mst@redhat.com> | |
| Message-ID: <20260830023354.115333-1-physicalmtea@gmail.com> | |
| Signed-off-by: Sasha Levin <sashal@kernel.org> | |
| --- | |
| 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 1cc826742ac9c..f9547ede71be7 100644 | |
| --- a/drivers/vdpa/vdpa_user/vduse_dev.c | |
| +++ b/drivers/vdpa/vdpa_user/vduse_dev.c | |
| @@ -1837,7 +1837,9 @@ static bool vduse_validate_config(struct vduse_dev_config *config) | |
| sizeof(config->reserved))) | |
| 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) | |
| -- | |
| 2.53.0 | |