| 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-2024-57877: arm64: ptrace: fix partial SETREGSET for NT_ARM_POE |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| arm64: ptrace: fix partial SETREGSET for NT_ARM_POE |
| |
| Currently poe_set() doesn't initialize the temporary 'ctrl' variable, |
| and a SETREGSET call with a length of zero will leave this |
| uninitialized. Consequently an arbitrary value will be written back to |
| target->thread.por_el0, potentially leaking up to 64 bits of memory from |
| the kernel stack. The read is limited to a specific slot on the stack, |
| and the issue does not provide a write mechanism. |
| |
| Fix this by initializing the temporary value before copying the regset |
| from userspace, as for other regsets (e.g. NT_PRSTATUS, NT_PRFPREG, |
| NT_ARM_SYSTEM_CALL). In the case of a zero-length write, the existing |
| contents of POR_EL1 will be retained. |
| |
| Before this patch: |
| |
| | # ./poe-test |
| | Attempting to write NT_ARM_POE::por_el0 = 0x900d900d900d900d |
| | SETREGSET(nt=0x40f, len=8) wrote 8 bytes |
| | |
| | Attempting to read NT_ARM_POE::por_el0 |
| | GETREGSET(nt=0x40f, len=8) read 8 bytes |
| | Read NT_ARM_POE::por_el0 = 0x900d900d900d900d |
| | |
| | Attempting to write NT_ARM_POE (zero length) |
| | SETREGSET(nt=0x40f, len=0) wrote 0 bytes |
| | |
| | Attempting to read NT_ARM_POE::por_el0 |
| | GETREGSET(nt=0x40f, len=8) read 8 bytes |
| | Read NT_ARM_POE::por_el0 = 0xffff8000839c3d50 |
| |
| After this patch: |
| |
| | # ./poe-test |
| | Attempting to write NT_ARM_POE::por_el0 = 0x900d900d900d900d |
| | SETREGSET(nt=0x40f, len=8) wrote 8 bytes |
| | |
| | Attempting to read NT_ARM_POE::por_el0 |
| | GETREGSET(nt=0x40f, len=8) read 8 bytes |
| | Read NT_ARM_POE::por_el0 = 0x900d900d900d900d |
| | |
| | Attempting to write NT_ARM_POE (zero length) |
| | SETREGSET(nt=0x40f, len=0) wrote 0 bytes |
| | |
| | Attempting to read NT_ARM_POE::por_el0 |
| | GETREGSET(nt=0x40f, len=8) read 8 bytes |
| | Read NT_ARM_POE::por_el0 = 0x900d900d900d900d |
| |
| The Linux kernel CVE team has assigned CVE-2024-57877 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.12 with commit 17519819926211e6b2834e00e4554bec0daf22ac and fixed in 6.12.5 with commit 4105dd76bc8ad6529d47157ef0565cb84ca6676c |
| Issue introduced in 6.12 with commit 17519819926211e6b2834e00e4554bec0daf22ac and fixed in 6.13 with commit 594bfc4947c4fcabba1318d8384c61a29a6b89fb |
| |
| 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-2024-57877 |
| 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/arm64/kernel/ptrace.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/4105dd76bc8ad6529d47157ef0565cb84ca6676c |
| https://git.kernel.org/stable/c/594bfc4947c4fcabba1318d8384c61a29a6b89fb |
