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vduse: check that offset is within bounds in get_config()

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This condition checks "len" but it does not check "offset" and that
could result in an out of bounds read if "offset > dev->config_size".
The problem is that since both variables are unsigned the
"dev->config_size - offset" subtraction would result in a very high
unsigned value.

I think these checks might not be necessary because "len" and "offset"
are supposed to already have been validated using the
vhost_vdpa_config_validate() function.  But I do not know the code
perfectly, and I like to be safe.

Fixes: c8a6153b6c ("vduse: Introduce VDUSE - vDPA Device in Userspace")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20211208150956.GA29160@kili
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Dan Carpenter 2021-12-08 18:09:56 +03:00 committed by Michael S. Tsirkin
parent 3ed21c1451
commit dc1db0060c
1 changed files with 2 additions and 1 deletions
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3
drivers/vdpa/vdpa_user/vduse_dev.c
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@ -655,7 +655,8 @@ static void vduse_vdpa_get_config(struct vdpa_device *vdpa, unsigned int offset,
{
struct vduse_dev *dev = vdpa_to_vduse(vdpa);
if (len > dev->config_size - offset)
if (offset > dev->config_size ||
len > dev->config_size - offset)
return;
memcpy(buf, dev->config + offset, len);