Date: Mon, 30 Nov 2020 17:07:43 +0100 From: Mauro Matteo Cascella <mcascell@...hat.com> To: oss-security@...ts.openwall.com Cc: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, "Xen.org security team" <security-team-members@....org> Subject: Re: Xen Security Advisory 355 v2 - stack corruption from XSA-346 change Hello, Has a CVE been assigned for this issue? Regards, On Tue, Nov 24, 2020 at 1:06 PM Xen.org security team <security@....org> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > Xen Security Advisory XSA-355 > version 2 > > stack corruption from XSA-346 change > > UPDATES IN VERSION 2 > ==================== > > Added metadata file. > > Public release. > > ISSUE DESCRIPTION > ================= > > One of the two changes for XSA-346 introduced an on-stack array. The > check for guarding against overrunning this array was off by one, > allowing for corruption of the first stack slot immediately following > this array. > > IMPACT > ====== > > A malicious or buggy HVM or PVH guest can cause Xen to crash, resulting > in a Denial of Service (DoS) to the entire host. Privilege escalation > as well as information leaks cannot be excluded. > > VULNERABLE SYSTEMS > ================== > > All Xen versions which have the patches for XSA-346 applied are > vulnerable. > > Only x86 HVM and PVH guests can leverage the vulnerability. Arm guests > and x86 PV guests cannot leverage the vulnerability. > > Only x86 HVM and PVH guests which have physical devices passed through > to them can leverage the vulnerability. > > MITIGATION > ========== > > Not passing through physical devices to untrusted guests will avoid > the vulnerability. > > CREDITS > ======= > > This issue was discovered by Jan Beulich of SUSE. > > RESOLUTION > ========== > > Applying the attached patch resolves this issue. > > Note that patches for released versions are generally prepared to > apply to the stable branches, and may not apply cleanly to the most > recent release tarball. Downstreams are encouraged to update to the > tip of the stable branch before applying these patches. > > xsa355.patch xen-unstable - Xen 4.10.x > > $ sha256sum xsa355* > a93bfc376897e7cffd095d395f1a66476adb9503d7d80a59b7861e64c2675323 xsa355.meta > dae633c11cf2eff3e304737265e18ab09213e8e4640458080a944ae7a40819a4 xsa355.patch > $ > > NOTE CONCERNING SHORT EMBARGO > ============================= > > This issue is likely to be re-discovered as the changes for XSA-346 > are deployed more widely, since the issue is also triggerable without > any malice or bugginess. > > DEPLOYMENT DURING EMBARGO > ========================= > > Deployment of the patches and/or mitigations described above (or > others which are substantially similar) is permitted during the > embargo, even on public-facing systems with untrusted guest users and > administrators. > > But: Distribution of updated software is prohibited (except to other > members of the predisclosure list). > > Predisclosure list members who wish to deploy significantly different > patches and/or mitigations, please contact the Xen Project Security > Team. > > (Note: this during-embargo deployment notice is retained in > post-embargo publicly released Xen Project advisories, even though it > is then no longer applicable. This is to enable the community to have > oversight of the Xen Project Security Team's decisionmaking.) > > For more information about permissible uses of embargoed information, > consult the Xen Project community's agreed Security Policy: > http://www.xenproject.org/security-policy.html > -----BEGIN PGP SIGNATURE----- > > iQFABAEBCAAqFiEEI+MiLBRfRHX6gGCng/4UyVfoK9kFAl+89pEMHHBncEB4ZW4u > b3JnAAoJEIP+FMlX6CvZRHQH/1D8CfjZWYgLcdYOg6sDO6BIK8IsnAiOoe2C8b9i > M8QPFzHlUx09FI5CHVb0Va/pFliR1OS2tmmIU30DL9nmiDLcaP2uvpgJAYo5GwL5 > Rzccjo4qbXwfSRQvHmLzbr+XN8sHDxbekpFd8T5WvuarUgxOaPCLTfSG0nag/t52 > OVNIdDcP5lSt/Z88lYW75j4gBAsXUZDEXgn81JpeHj9js8YLFC3WFcwh58Jjd+hw > 5DH955jNAKD8TRSy6uffDpvN1m9wm2vDGeXSUcJyswlV8Nqi6YRW4XO4Q6Cfj+CG > LVBS/T977JZGJjRvTw4j0H+xAXiLFwQ1I/6v6fSZzxDMt9k= > =+4M1 > -----END PGP SIGNATURE----- -- Mauro Matteo Cascella Red Hat Product Security PGP-Key ID: BB3410B0
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