| 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-2021-46971: perf/core: Fix unconditional security_locked_down() call |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| perf/core: Fix unconditional security_locked_down() call |
| |
| Currently, the lockdown state is queried unconditionally, even though |
| its result is used only if the PERF_SAMPLE_REGS_INTR bit is set in |
| attr.sample_type. While that doesn't matter in case of the Lockdown LSM, |
| it causes trouble with the SELinux's lockdown hook implementation. |
| |
| SELinux implements the locked_down hook with a check whether the current |
| task's type has the corresponding "lockdown" class permission |
| ("integrity" or "confidentiality") allowed in the policy. This means |
| that calling the hook when the access control decision would be ignored |
| generates a bogus permission check and audit record. |
| |
| Fix this by checking sample_type first and only calling the hook when |
| its result would be honored. |
| |
| The Linux kernel CVE team has assigned CVE-2021-46971 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.4 with commit b0c8fdc7fdb77586c3d1937050925b960743306e and fixed in 5.4.117 with commit b246759284d6a2bc5b6f1009caeeb3abce2ec9ff |
| Issue introduced in 5.4 with commit b0c8fdc7fdb77586c3d1937050925b960743306e and fixed in 5.10.35 with commit 4348d3b5027bc3ff6336368b6c60605d4ef8e1ce |
| Issue introduced in 5.4 with commit b0c8fdc7fdb77586c3d1937050925b960743306e and fixed in 5.11.19 with commit f5809ca4c311b71bfaba6d13f4e39eab0557895e |
| Issue introduced in 5.4 with commit b0c8fdc7fdb77586c3d1937050925b960743306e and fixed in 5.12.2 with commit c7b0208ee370b89d20486fae71cd9abb759819c1 |
| Issue introduced in 5.4 with commit b0c8fdc7fdb77586c3d1937050925b960743306e and fixed in 5.13 with commit 08ef1af4de5fe7de9c6d69f1e22e51b66e385d9b |
| |
| 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-2021-46971 |
| 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: |
| kernel/events/core.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/b246759284d6a2bc5b6f1009caeeb3abce2ec9ff |
| https://git.kernel.org/stable/c/4348d3b5027bc3ff6336368b6c60605d4ef8e1ce |
| https://git.kernel.org/stable/c/f5809ca4c311b71bfaba6d13f4e39eab0557895e |
| https://git.kernel.org/stable/c/c7b0208ee370b89d20486fae71cd9abb759819c1 |
| https://git.kernel.org/stable/c/08ef1af4de5fe7de9c6d69f1e22e51b66e385d9b |
