| 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-2023-52476: perf/x86/lbr: Filter vsyscall addresses |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| perf/x86/lbr: Filter vsyscall addresses |
| |
| We found that a panic can occur when a vsyscall is made while LBR sampling |
| is active. If the vsyscall is interrupted (NMI) for perf sampling, this |
| call sequence can occur (most recent at top): |
| |
| __insn_get_emulate_prefix() |
| insn_get_emulate_prefix() |
| insn_get_prefixes() |
| insn_get_opcode() |
| decode_branch_type() |
| get_branch_type() |
| intel_pmu_lbr_filter() |
| intel_pmu_handle_irq() |
| perf_event_nmi_handler() |
| |
| Within __insn_get_emulate_prefix() at frame 0, a macro is called: |
| |
| peek_nbyte_next(insn_byte_t, insn, i) |
| |
| Within this macro, this dereference occurs: |
| |
| (insn)->next_byte |
| |
| Inspecting registers at this point, the value of the next_byte field is the |
| address of the vsyscall made, for example the location of the vsyscall |
| version of gettimeofday() at 0xffffffffff600000. The access to an address |
| in the vsyscall region will trigger an oops due to an unhandled page fault. |
| |
| To fix the bug, filtering for vsyscalls can be done when |
| determining the branch type. This patch will return |
| a "none" branch if a kernel address if found to lie in the |
| vsyscall region. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52476 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.15.137 with commit 403d201d1fd144cb249836dafb222f6375871c6c |
| Fixed in 6.1.59 with commit 3863989497652488a50f00e96de4331e5efabc6c |
| Fixed in 6.5.8 with commit f71edacbd4f99c0e12fe4a4007ab4d687d0688db |
| Fixed in 6.6 with commit e53899771a02f798d436655efbd9d4b46c0f9265 |
| |
| 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-2023-52476 |
| 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: |
| arch/x86/events/utils.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/403d201d1fd144cb249836dafb222f6375871c6c |
| https://git.kernel.org/stable/c/3863989497652488a50f00e96de4331e5efabc6c |
| https://git.kernel.org/stable/c/f71edacbd4f99c0e12fe4a4007ab4d687d0688db |
| https://git.kernel.org/stable/c/e53899771a02f798d436655efbd9d4b46c0f9265 |
