| 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-2024-57878: arm64: ptrace: fix partial SETREGSET for NT_ARM_FPMR |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| arm64: ptrace: fix partial SETREGSET for NT_ARM_FPMR |
| |
| Currently fpmr_set() doesn't initialize the temporary 'fpmr' 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.uw.fpmr, 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 FPMR will be retained. |
| |
| Before this patch: |
| |
| | # ./fpmr-test |
| | Attempting to write NT_ARM_FPMR::fpmr = 0x900d900d900d900d |
| | SETREGSET(nt=0x40e, len=8) wrote 8 bytes |
| | |
| | Attempting to read NT_ARM_FPMR::fpmr |
| | GETREGSET(nt=0x40e, len=8) read 8 bytes |
| | Read NT_ARM_FPMR::fpmr = 0x900d900d900d900d |
| | |
| | Attempting to write NT_ARM_FPMR (zero length) |
| | SETREGSET(nt=0x40e, len=0) wrote 0 bytes |
| | |
| | Attempting to read NT_ARM_FPMR::fpmr |
| | GETREGSET(nt=0x40e, len=8) read 8 bytes |
| | Read NT_ARM_FPMR::fpmr = 0xffff800083963d50 |
| |
| After this patch: |
| |
| | # ./fpmr-test |
| | Attempting to write NT_ARM_FPMR::fpmr = 0x900d900d900d900d |
| | SETREGSET(nt=0x40e, len=8) wrote 8 bytes |
| | |
| | Attempting to read NT_ARM_FPMR::fpmr |
| | GETREGSET(nt=0x40e, len=8) read 8 bytes |
| | Read NT_ARM_FPMR::fpmr = 0x900d900d900d900d |
| | |
| | Attempting to write NT_ARM_FPMR (zero length) |
| | SETREGSET(nt=0x40e, len=0) wrote 0 bytes |
| | |
| | Attempting to read NT_ARM_FPMR::fpmr |
| | GETREGSET(nt=0x40e, len=8) read 8 bytes |
| | Read NT_ARM_FPMR::fpmr = 0x900d900d900d900d |
| |
| The Linux kernel CVE team has assigned CVE-2024-57878 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.9 with commit 4035c22ef7d43a6c00d6a6584c60e902b95b46af and fixed in 6.12.5 with commit 8ab73c34e3c5b580721696665eabd799346bc50b |
| Issue introduced in 6.9 with commit 4035c22ef7d43a6c00d6a6584c60e902b95b46af and fixed in 6.13 with commit f5d71291841aecfe5d8435da2dfa7f58ccd18bc8 |
| |
| 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-2024-57878 |
| 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/8ab73c34e3c5b580721696665eabd799346bc50b |
| https://git.kernel.org/stable/c/f5d71291841aecfe5d8435da2dfa7f58ccd18bc8 |
