On Mon, Feb 15, 2021 at 03:32:19PM +0100, Greg KH wrote:
On Thu, Feb 11, 2021 at 05:25:19PM +0100, Stefano Garzarella wrote:
Commit 65b709586e222fa6ffd4166ac7fdb5d5dad113ee upstream.
No, this really is not that commit, so please do not say it is.
Oops, sorry.
Before this patch, if 'offset + len' was equal to
sizeof(struct virtio_net_config), the entire buffer wasn't filled,
returning incorrect values to the caller.
Since 'vdpasim->config' type is 'struct virtio_net_config', we can
safely copy its content under this condition.
Commit 65b709586e22 ("vdpa_sim: add get_config callback in
vdpasim_dev_attr") unintentionally solved it upstream while
refactoring vdpa_sim.c to support multiple devices. But we don't want
to backport it to stable branches as it contains many changes.
Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator")
Cc: <sta...@vger.kernel.org> # 5.10.x
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 6a90fdb9cbfc..8ca178d7b02f 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -572,7 +572,7 @@ static void vdpasim_get_config(struct vdpa_device *vdpa,
unsigned int offset,
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
- if (offset + len < sizeof(struct virtio_net_config))
+ if (offset + len <= sizeof(struct virtio_net_config))
memcpy(buf, (u8 *)&vdpasim->config + offset, len);
}
I'll be glad to take a one-off patch, but why can't we take the real
upstream patch? That is always the better long-term solution, right?
Because that patch depends on the following patches merged in v5.11-rc1
while refactoring vdpa_sim:
f37cbbc65178 vdpa_sim: make 'config' generic and usable for any device type
cf1a3b35382c vdpa_sim: store parsed MAC address in a buffer
a13b5918fdd0 vdpa_sim: add work_fn in vdpasim_dev_attr
011c35bac5ef vdpa_sim: add supported_features field in vdpasim_dev_attr
2f8f46188805 vdpa_sim: add device id field in vdpasim_dev_attr
6c6e28fe4579 vdpa_sim: add struct vdpasim_dev_attr for device attributes
36a9c3063025 vdpa_sim: rename vdpasim_config_ops variables
423248d60d2b vdpa_sim: remove hard-coded virtq count
Maybe we can skip some of them, but IMHO should be less risky to apply
only this change.
If you want I can try to figure out the minimum sub-set of patches
needed for 65b709586e22 ("vdpa_sim: add get_config callback in
vdpasim_dev_attr").
Thanks,
Stefano
