| 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-2024-26603: x86/fpu: Stop relying on userspace for info to fault in xsave buffer |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| x86/fpu: Stop relying on userspace for info to fault in xsave buffer |
| |
| Before this change, the expected size of the user space buffer was |
| taken from fx_sw->xstate_size. fx_sw->xstate_size can be changed |
| from user-space, so it is possible construct a sigreturn frame where: |
| |
| * fx_sw->xstate_size is smaller than the size required by valid bits in |
| fx_sw->xfeatures. |
| * user-space unmaps parts of the sigrame fpu buffer so that not all of |
| the buffer required by xrstor is accessible. |
| |
| In this case, xrstor tries to restore and accesses the unmapped area |
| which results in a fault. But fault_in_readable succeeds because buf + |
| fx_sw->xstate_size is within the still mapped area, so it goes back and |
| tries xrstor again. It will spin in this loop forever. |
| |
| Instead, fault in the maximum size which can be touched by XRSTOR (taken |
| from fpstate->user_size). |
| |
| [ dhansen: tweak subject / changelog ] |
| |
| The Linux kernel CVE team has assigned CVE-2024-26603 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.14 with commit fcb3635f5018e53024c6be3c3213737f469f74ff and fixed in 5.15.150 with commit 8bd3eee7720c14b59a206bd05b98d7586bccf99a |
| Issue introduced in 5.14 with commit fcb3635f5018e53024c6be3c3213737f469f74ff and fixed in 6.1.79 with commit 627339cccdc9166792ecf96bc3c9f711a60ce996 |
| Issue introduced in 5.14 with commit fcb3635f5018e53024c6be3c3213737f469f74ff and fixed in 6.6.18 with commit b2479ab426cef7ab79a13005650eff956223ced2 |
| Issue introduced in 5.14 with commit fcb3635f5018e53024c6be3c3213737f469f74ff and fixed in 6.7.6 with commit 627e28cbb65564e55008315d9e02fbb90478beda |
| Issue introduced in 5.14 with commit fcb3635f5018e53024c6be3c3213737f469f74ff and fixed in 6.8 with commit d877550eaf2dc9090d782864c96939397a3c6835 |
| |
| 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-2024-26603 |
| 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/kernel/fpu/signal.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/8bd3eee7720c14b59a206bd05b98d7586bccf99a |
| https://git.kernel.org/stable/c/627339cccdc9166792ecf96bc3c9f711a60ce996 |
| https://git.kernel.org/stable/c/b2479ab426cef7ab79a13005650eff956223ced2 |
| https://git.kernel.org/stable/c/627e28cbb65564e55008315d9e02fbb90478beda |
| https://git.kernel.org/stable/c/d877550eaf2dc9090d782864c96939397a3c6835 |
