xen/gntdev: Prevent leaking grants (CVE-2022-50257)

Summary

xen/gntdev: Prevent leaking grants

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

xen/gntdev: Prevent leaking grants

Prior to this commit, if a grant mapping operation failed partially,
some of the entries in the map_ops array would be invalid, whereas all
of the entries in the kmap_ops array would be valid. This in turn would
cause the following logic in gntdev_map_grant_pages to become invalid:

for (i = 0; i < map->count; i++) {
if (map->map_ops[i].status == GNTST_okay) {
map->unmap_ops[i].handle = map->map_ops[i].handle;
if (!use_ptemod)
alloced++;
}
if (use_ptemod) {
if (map->kmap_ops[i].status == GNTST_okay) {
if (map->map_ops[i].status == GNTST_okay)
alloced++;
map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
}
}
}
...
atomic_add(alloced, &map->live_grants);

Assume that use_ptemod is true (i.e., the domain mapping the granted
pages is a paravirtualized domain). In the code excerpt above, note that
the "alloced" variable is only incremented when both kmap_ops[i].status
and map_ops[i].status are set to GNTST_okay (i.e., both mapping
operations are successful). However, as also noted above, there are
cases where a grant mapping operation fails partially, breaking the
assumption of the code excerpt above.

The aforementioned causes map->live_grants to be incorrectly set. In
some cases, all of the map_ops mappings fail, but all of the kmap_ops
mappings succeed, meaning that live_grants may remain ze…

Source: OSV.dev (Open Source Vulnerabilities) NVD OSV

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.9.332"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.10.0"},{"fixed":"4.14.298"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.15.0"},{"fixed":"4.19.264"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"5.4.223"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.153"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.75"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"5.19.17"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.19.0"},{"fixed":"6.0.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2022-50257 linux Fixed in: 5.10.158-1
Ubuntu UBUNTU-CVE-2022-50257 linux-azure Fixed in: 4.15.0-1162.177~14.04.1

Summary

Original description

Affected packages

Fix status by distribution

References