Date: Tue, 20 Oct 2020 12:00:33 +0000 From: Xen.org security team <security@....org> To: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com CC: Xen.org security team <security-team-members@....org> Subject: Xen Security Advisory 331 v2 - Race condition in Linux event handler may crash dom0 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory XSA-331 version 2 Race condition in Linux event handler may crash dom0 UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= The Linux kernel event channel handling code doesn't defend the handling of an event against the same event channel being removed in parallel. This can result in accesses to already freed memory areas or NULL pointer dereferences in the event handling code, leading to misbehaviour of the system or even crashes. IMPACT ====== A misbehaving guest can trigger a dom0 crash by sending events for a paravirtualized device while simultaneously reconfiguring it. VULNERABLE SYSTEMS ================== All systems with a Linux dom0 are vulnerable. All Linux kernel versions are vulnerable. MITIGATION ========== There is no known mitigation. CREDITS ======= This issue was discovered by Jinoh Kang of Theori. 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. xsa331-linux.patch Linux $ sha256sum xsa331* 8583392c0c573f7baa85e41c9afbdf74dcb04aea1be992d78991f0787230a193 xsa331-linux.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deployment notice is retained in post-embargo publicly released Xen Project advisories, even though it is then no longer applicable.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/4UyVfoK9kFAl+OzqMMHHBncEB4ZW4u b3JnAAoJEIP+FMlX6CvZuo4H/R4b4Z7ZTMwwpL4u3PrguNZduaTc3vy9R+Gd0+5z hY0Zfif7SfhJ2apN4Ihs1eAGxyWLI/I8kQQGE4xKgZy2ygciMbTK0OCsoGxfEr6v bi4RKV9I03g3fQHy48z+lOt4XKTY8+OpHw8LYY3W7jdnQ0YJrPCOmap0Xkv91QhP +EkmxzahVQv0T16cP4fxZFUvY0M9gijEjE9h9Gv23M+tLP9SGkW9Hd11qM135AKh vVSYUIuvyd20zb5uiqXono9qP1CeKyCOXHL+YQ+K7eOjYCVbEDdREneBegFlS9By jaFukH/psQDdemQDT4amzOmtBzdImIzkGhflvj+b5axRlrw= =FLDG -----END PGP SIGNATURE----- Download attachment "xsa331-linux.patch" of type "application/octet-stream" (4730 bytes)
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.