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 <[email protected]>
---
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
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -2190,7 +2190,9 @@ 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)
