[Pkg-xen-devel] Bug#1033297: xen: CVE-2022-42331 CVE-2022-42332 CVE-2022-42333 CVE-2022-42334

[Salvatore Bonaccorso]

Source: xen
Version: 4.17.0+46-gaaf74a532c-1
Severity: grave
Tags: security upstream
X-Debbugs-Cc: carnil at debian.org, Debian Security Team <team at security.debian.org>

Hi,

The following vulnerabilities were published for xen.

CVE-2022-42331[0]:
| x86: speculative vulnerability in 32bit SYSCALL path Due to an
| oversight in the very original Spectre/Meltdown security work
| (XSA-254), one entrypath performs its speculation-safety actions too
| late. In some configurations, there is an unprotected RET instruction
| which can be attacked with a variety of speculative attacks.


CVE-2022-42332[1]:
| x86 shadow plus log-dirty mode use-after-free In environments where
| host assisted address translation is necessary but Hardware Assisted
| Paging (HAP) is unavailable, Xen will run guests in so called shadow
| mode. Shadow mode maintains a pool of memory used for both shadow page
| tables as well as auxiliary data structures. To migrate or snapshot
| guests, Xen additionally runs them in so called log-dirty mode. The
| data structures needed by the log-dirty tracking are part of
| aformentioned auxiliary data. In order to keep error handling efforts
| within reasonable bounds, for operations which may require memory
| allocations shadow mode logic ensures up front that enough memory is
| available for the worst case requirements. Unfortunately, while page
| table memory is properly accounted for on the code path requiring the
| potential establishing of new shadows, demands by the log-dirty
| infrastructure were not taken into consideration. As a result, just
| established shadow page tables could be freed again immediately, while
| other code is still accessing them on the assumption that they would
| remain allocated.


CVE-2022-42333[2]:
| x86/HVM pinned cache attributes mis-handling T[his CNA information
| record relates to multiple CVEs; the text explains which
| aspects/vulnerabilities correspond to which CVE.] To allow cachability
| control for HVM guests with passed through devices, an interface
| exists to explicitly override defaults which would otherwise be put in
| place. While not exposed to the affected guests themselves, the
| interface specifically exists for domains controlling such guests.
| This interface may therefore be used by not fully privileged entities,
| e.g. qemu running deprivileged in Dom0 or qemu running in a so called
| stub-domain. With this exposure it is an issue that - the number of
| the such controlled regions was unbounded (CVE-2022-42333), -
| installation and removal of such regions was not properly serialized
| (CVE-2022-42334).


CVE-2022-42334[3]:
| x86/HVM pinned cache attributes mis-handling T[his CNA information
| record relates to multiple CVEs; the text explains which
| aspects/vulnerabilities correspond to which CVE.] To allow cachability
| control for HVM guests with passed through devices, an interface
| exists to explicitly override defaults which would otherwise be put in
| place. While not exposed to the affected guests themselves, the
| interface specifically exists for domains controlling such guests.
| This interface may therefore be used by not fully privileged entities,
| e.g. qemu running deprivileged in Dom0 or qemu running in a so called
| stub-domain. With this exposure it is an issue that - the number of
| the such controlled regions was unbounded (CVE-2022-42333), -
| installation and removal of such regions was not properly serialized
| (CVE-2022-42334).


If you fix the vulnerabilities please also make sure to include the
CVE (Common Vulnerabilities & Exposures) ids in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2022-42331
    https://www.cve.org/CVERecord?id=CVE-2022-42331
[1] https://security-tracker.debian.org/tracker/CVE-2022-42332
    https://www.cve.org/CVERecord?id=CVE-2022-42332
[2] https://security-tracker.debian.org/tracker/CVE-2022-42333
    https://www.cve.org/CVERecord?id=CVE-2022-42333
[3] https://security-tracker.debian.org/tracker/CVE-2022-42334
    https://www.cve.org/CVERecord?id=CVE-2022-42334

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore