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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.2888 New Xen bulletin: xen/arm: No memory limit for dom0less domUs 26 August 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Xen Publisher: Xen Operating System: Xen Impact/Access: Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2021-28700 Original Bulletin: http://xenbits.xen.org/xsa/advisory-383.txt - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory CVE-2021-28700 / XSA-383 version 2 xen/arm: No memory limit for dom0less domUs UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= The dom0less feature allows an administrator to create multiple unprivileged domains directly from Xen. Unfortunately, the memory limit from them is not set. This allow a domain to allocate memory beyond what an administrator originally configured. IMPACT ====== Malicious dom0less guest could drive Xen out of memory and may result to a Denial of Service (DoS) attack affecting the entire system. VULNERABLE SYSTEMS ================== Only Arm systems are vulnerable. Only domains created using the dom0less feature are affected. Only domains created using the dom0less feature can leverage the vulnerability. All versions of Xen since 4.12 are vulnerable. MITIGATION ========== There is no known mitigation. CREDITS ======= This issue was discovered by Julien Grall of Amazon. RESOLUTION ========== Applying the appropriate 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. xsa383.patch xen-unstable - Xen 4.13.x xsa383-4.12.patch Xen 4.12.x $ sha256sum xsa383* 773fe38d5d182ce43b5552fcdf6ed08c33126ed728e40d94c5050f89bfb3bd4d xsa383.meta cfd0632d250cc36d88269ae08e19e742c6bd07ba130c2604d51a10ba64d4e413 xsa383.patch d18f72fa595f330fa8ed13c9412a36fba58a8baf9ad30b9fc2fd4e4533c0ee1a xsa383-4.12.patch $ 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/4UyVfoK9kFAmEmMPYMHHBncEB4ZW4u b3JnAAoJEIP+FMlX6CvZmboIALCcOpac8K7jPXZ+D5S5S1kGExOHYCLDBCZ6LyPt jUmuR3r7xnkpJmcwSqGBHF5/PR6Sug+AjiggR8WHAFYiKod7yt1NjR4dm92Jy89x t4mpyQ2ZX7PIMOiTfxlsmzsDspBxjk9sV6Pt7w4o25MiWdmY41hEkE+qtJ0OBto0 btzbaInKko6SXZWPGGpAToKlKPnwcApe2DehGYO98xl8eUZ8Ql/1lieHjuSK60Nx RlboPeGDZwDgDroRj8GFNGxl2hESULVof0tG3w2IXPmYoa9iTKNUnO3KFL4kAJ/p ZWzyRuHbX9FjQXBFnJJ5pyTHrc1aYzXJCwxAoSt436aRX2c= =NGUO - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBYSctVuNLKJtyKPYoAQjZ/Q/8D/kjpJjG0UtESZY9dsTkDyeH2WjZzfP3 NSRny0hbtUzpZfRSg06j/Caq6nusp9CCMKG9uv14ibINqc0MhTgJwTbhfp6A5u+u AnvCPMN68CwOmIOhXcvsirYyoS4pP6enhzgC/1b6hBNqlvG4Pd66BE9Q0Vf8Drc+ dtzV+D38seQ5CrPAyBTuEhb9lyn1t9BSH0UxlDaN0aVqFK4E8dgbTO5KPh2Ved+H lDHeG27QC347Xk6mIxC3pLc/feWIUW8YH8QnEIX+rUGtCwkCO4RfrUJGmjoX4FLh Ghzj8MeBiQ4TaWVzGFlAHryKRRe7EKh9aqNUtHltwbfURz6vE/FLE9/WGBPhmKWE lc75nCVlsSnLG56HzZrVwdA8kT8BGgG4zN2kaQRsRzJpoYFn64Neoq2zogm66LOV UaKTRukJDuiO1UF1DgGnTcBYPay2Fj4iRw2QLQjw3W+zBbAYws8tZ06lQiirTSko J/cm7b8pfXqpwBMVlXnLSZk1eqJ/1BHm5gLw74pBvMW8WkQRgxW+1u+PLxUEiiue LnDf/3GHHG24ByxoFMYpDANRI5aYP+IE683HrA/vVpcdo/C7nOKe4WXkVOUtHzu/ gz9ogF3pGUn6w0EpniJ3N/J13S0YmVPD44jN16GdNx8ZX2yMkaJvVEyDKOQoWq0Z vcgxentPW70= =IcAm -----END PGP SIGNATURE-----