CVE-2023-52792

In the Linux kernel, the following vulnerability has been resolved:
cxl/region: Do not try to cleanup after cxl_region_setup_targets() fails
Commit 5e42bcbc3fef (“cxl/region: decrement ->nr_targets on error in
cxl_region_attach()”) tried to avoid ‘eiw’ initialization errors when
->nr_targets exceeded 16, by just decrementing ->nr_targets when
cxl_region_setup_targets() failed. Commit 86987c766276 (“cxl/region:
Cleanup target list on attach error”) extended that cleanup to also clear
cxled->pos and p->targets[pos]. The initialization error was incidentally
fixed separately by: Commit 8d4285425714 (“cxl/region: Fix port setup
uninitialized variable warnings”) which was merged a few days after
5e42bcbc3fef. But now the original cleanup when cxl_region_setup_targets()
fails prevents endpoint and switch decoder resources from being reused: 1)
the cleanup does not set the decoder’s region to NULL, which results in
future dpa_size_store() calls returning -EBUSY 2) the decoder is not
properly freed, which results in future commit errors associated with the
upstream switch Now that the initialization errors were fixed separately,
the proper cleanup for this case is to just return immediately. Then the
resources associated with this target get cleanup up as normal when the
failed region is deleted. The ->nr_targets decrement in the error case also
helped prevent a p->targets[] array overflow, so add a new check to prevent
against that overflow. Tested by trying to create an invalid region for a 2
switch * 2 endpoint topology, and then following up with creating a valid
region.