| 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-2022-48988: memcg: fix possible use-after-free in memcg_write_event_control() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| memcg: fix possible use-after-free in memcg_write_event_control() |
| |
| memcg_write_event_control() accesses the dentry->d_name of the specified |
| control fd to route the write call. As a cgroup interface file can't be |
| renamed, it's safe to access d_name as long as the specified file is a |
| regular cgroup file. Also, as these cgroup interface files can't be |
| removed before the directory, it's safe to access the parent too. |
| |
| Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a |
| call to __file_cft() which verified that the specified file is a regular |
| cgroupfs file before further accesses. The cftype pointer returned from |
| __file_cft() was no longer necessary and the commit inadvertently dropped |
| the file type check with it allowing any file to slip through. With the |
| invarients broken, the d_name and parent accesses can now race against |
| renames and removals of arbitrary files and cause use-after-free's. |
| |
| Fix the bug by resurrecting the file type check in __file_cft(). Now that |
| cgroupfs is implemented through kernfs, checking the file operations needs |
| to go through a layer of indirection. Instead, let's check the superblock |
| and dentry type. |
| |
| The Linux kernel CVE team has assigned CVE-2022-48988 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 4.14.302 with commit b77600e26fd48727a95ffd50ba1e937efb548125 |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 4.19.269 with commit e1ae97624ecf400ea56c238bff23e5cd139df0b8 |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 5.4.227 with commit 35963b31821920908e397146502066f6b032c917 |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 5.10.159 with commit f1f7f36cf682fa59db15e2089039a2eeb58ff2ad |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 5.15.83 with commit aad8bbd17a1d586005feb9226c2e9cfce1432e13 |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 6.0.13 with commit 0ed074317b835caa6c03bcfa8f133365324673dc |
| Issue introduced in 3.14 with commit 347c4a8747104a945ecced358944e42879176ca5 and fixed in 6.1 with commit 4a7ba45b1a435e7097ca0f79a847d0949d0eb088 |
| |
| 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-2022-48988 |
| 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: |
| include/linux/cgroup.h |
| kernel/cgroup/cgroup-internal.h |
| mm/memcontrol.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/b77600e26fd48727a95ffd50ba1e937efb548125 |
| https://git.kernel.org/stable/c/e1ae97624ecf400ea56c238bff23e5cd139df0b8 |
| https://git.kernel.org/stable/c/35963b31821920908e397146502066f6b032c917 |
| https://git.kernel.org/stable/c/f1f7f36cf682fa59db15e2089039a2eeb58ff2ad |
| https://git.kernel.org/stable/c/aad8bbd17a1d586005feb9226c2e9cfce1432e13 |
| https://git.kernel.org/stable/c/0ed074317b835caa6c03bcfa8f133365324673dc |
| https://git.kernel.org/stable/c/4a7ba45b1a435e7097ca0f79a847d0949d0eb088 |
