Bugzilla – Full Text Bug Listing
|Summary:||VUL-0: CVE-2021-28039: xen: Linux: special config may crash when trying to map foreign pages (XSA-369)|
|Product:||[Novell Products] SUSE Security Incidents||Reporter:||Robert Frohl <rfrohl>|
|Component:||Incidents||Assignee:||Security Team bot <security-team>|
|Status:||RESOLVED INVALID||QA Contact:||Security Team bot <security-team>|
|Priority:||P3 - Medium||CC:||bpetkov, carnold, gianluca.gabrielli, jgross|
|Found By:||---||Services Priority:|
|Marketing QA Status:||---||IT Deployment:||---|
Description Robert Frohl 2021-03-05 08:48:14 UTC
Created attachment 846821 [details] patch Xen Security Advisory XSA-369 Linux: special config may crash when trying to map foreign pages ISSUE DESCRIPTION ================= With CONFIG_XEN_BALLOON_MEMORY_HOTPLUG disabled and CONFIG_XEN_UNPOPULATED_ALLOC enabled the Linux kernel will use guest physical addresses allocated via the ZONE_DEVICE functionality for mapping foreign guest's pages. This will result in problems, as the p2m list will only cover the initial memory size of the domain plus some padding at the end. Most ZONE_DEVICE allocated addresses will be outside the p2m range and thus a mapping can't be established with those memory addresses, resulting in a crash. The attack involves doing I/O requiring large amounts of data to be mapped by the Dom0 or driver domain. The amount of data needed to result in a crash can vary depending on the memory layout of the affected Dom0 or driver domain. IMPACT ====== A Dom0 or driver domain based on a Linux kernel (configured as described above) can be crashed by a malicious guest administrator, or possibly malicious unprivileged guest processes. VULNERABLE SYSTEMS ================== Only x86 paravirtualized (PV) Dom0 or driver domains are affected. Only Linux kernels configured *with* CONFIG_XEN_UNPOPULATED_ALLOC and *without* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG are vulnerable. Only kernels from kernel version 5.9 onwards are affected. CONFIG_XEN_BALLOON_MEMORY_HOTPLUG is enabled by default in upstream Linux when Xen support is enabled, so kernels using upstream default Kconfig are not affected. Most distribution kernels supporting Xen dom0 use are likewise not vulnerable. Arm systems or x86 PVH or x86 HVM driver domains are not affected. MITIGATION ========== There is no mitigation available. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa369-linux.patch Linux 5.9-stable - 5.12-rc $ sha256sum xsa369* 937df4f078a070cf47bdd718c6b8a042ec6bee255eedc422d833c2ae3dd561c7 xsa369-linux.patch $ CREDITS ======= This issue was discovered by Marek Marczykowski-Górecki of Invisible Things Lab. For patch: Reported-by: Marek Marczykowski-Górecki <email@example.com> NOTE REGARDING LACK OF EMBARGO ============================== This was reported publicly multiple times, before the XSA could be issued.
Comment 3 Robert Frohl 2021-03-05 09:28:34 UTC
@kernel-bugs: also looks like a duplicate, for bsc#1183035
Comment 5 Jürgen Groß 2021-03-05 09:56:05 UTC
As only kernels from 5.9 onwards are affected, I don't see any action on our side to be necessary.
Comment 6 Borislav Petkov 2021-03-05 11:19:59 UTC
(In reply to Jürgen Groß from comment #5) > As only kernels from 5.9 onwards are affected, I don't see any action on our > side to be necessary. What about the master and stable branches? Or we don't support them with Xen?
Comment 7 Jürgen Groß 2021-03-05 11:26:35 UTC
master and stable will get the fix rather soon via upstream. The patches have already been taken there. The issue itself is of rather low severity and our default kernel config is not affected by the issue.
Comment 8 Borislav Petkov 2021-03-05 11:32:12 UTC
Ok, good, I guess we're done here then. Bouncing back.
Comment 9 Robert Frohl 2021-03-08 09:14:14 UTC
*** Bug 1183035 has been marked as a duplicate of this bug. ***
Comment 10 Robert Frohl 2022-01-11 14:10:00 UTC
nothing to do, closing