| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-47111: xen-netback: take a reference to the RX task thread |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| xen-netback: take a reference to the RX task thread |
| |
| Do this in order to prevent the task from being freed if the thread |
| returns (which can be triggered by the frontend) before the call to |
| kthread_stop done as part of the backend tear down. Not taking the |
| reference will lead to a use-after-free in that scenario. Such |
| reference was taken before but dropped as part of the rework done in |
| 2ac061ce97f4. |
| |
| Reintroduce the reference taking and add a comment this time |
| explaining why it's needed. |
| |
| This is XSA-374 / CVE-2021-28691. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47111 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.5 with commit 2ac061ce97f413bfbbdd768f7d2e0fda2e8170df and fixed in 5.10.43 with commit 6b53db8c4c14b4e7256f058d202908b54a7b85b4 |
| Issue introduced in 5.5 with commit 2ac061ce97f413bfbbdd768f7d2e0fda2e8170df and fixed in 5.12.10 with commit caec9bcaeb1a5f03f2d406305355c853af10c13e |
| Issue introduced in 5.5 with commit 2ac061ce97f413bfbbdd768f7d2e0fda2e8170df and fixed in 5.13 with commit 107866a8eb0b664675a260f1ba0655010fac1e08 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2021-47111 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/net/xen-netback/interface.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/6b53db8c4c14b4e7256f058d202908b54a7b85b4 |
| https://git.kernel.org/stable/c/caec9bcaeb1a5f03f2d406305355c853af10c13e |
| https://git.kernel.org/stable/c/107866a8eb0b664675a260f1ba0655010fac1e08 |
