CVE-2024-26670
- Source
- https://cve.org/CVERecord?id=CVE-2024-26670
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-26670.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2024-26670
- Downstream
BELL (1)
DEBIAN (1)
ECHO (1)
RHSA (1)
ROOT (1)
- Related
- Published
- 2024-04-02T06:43:31Z
- Modified
- 2026-10-08T02:49:34Z
- Severity
-
- 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- arm64: entry: fix ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
arm64: entry: fix ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
Currently the ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD workaround isn't quite right, as it is supposed to be applied after the last explicit memory access, but is immediately followed by an LDR.
The ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD workaround is used to handle Cortex-A520 erratum 2966298 and Cortex-A510 erratum 3117295, which are described in:
- https://developer.arm.com/documentation/SDEN2444153/0600/?lang=en
- https://developer.arm.com/documentation/SDEN1873361/1600/?lang=en
In both cases the workaround is described as:
| If pagetable isolation is disabled, the context switch logic in the | kernel can be updated to execute the following sequence on affected | cores before exiting to EL0, and after all explicit memory accesses: | | 1. A non-shareable TLBI to any context and/or address, including | unused contexts or addresses, such as a
TLBI VALE1 Xzr. | | 2. A DSB NSH to guarantee completion of the TLBI.The important part being that the TLBI+DSB must be placed "after all explicit memory accesses".
Unfortunately, as-implemented, the TLBI+DSB is immediately followed by an LDR, as we have:
| alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD | tlbi vale1, xzr | dsb nsh | alternative_else_nop_endif | alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 | ldr lr, [sp, #S_LR] | add sp, sp, #PT_REGS_SIZE // restore sp | eret | alternative_else_nop_endif | | [ ... KPTI exception return path ... ]
This patch fixes this by reworking the logic to place the TLBI+DSB immediately before the ERET, after all explicit memory accesses.
The ERET is currently in a separate alternative block, and alternatives cannot be nested. To account for this, the alternative block for ARM64_UNMAP_KERNEL_AT_EL0 is replaced with a single alternative branch to skip the KPTI logic, with the new shape of the logic being:
| alternative_insn "b .L_skip_tramp_exit_@", nop, ARM64_UNMAP_KERNEL_AT_EL0 | [ ... KPTI exception return path ... ] | .L_skip_tramp_exit_@: | | ldr lr, [sp, #S_LR] | add sp, sp, #PT_REGS_SIZE // restore sp | | alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD | tlbi vale1, xzr | dsb nsh | alternative_else_nop_endif | eret
The new structure means that the workaround is only applied when KPTI is not in use; this is fine as noted in the documented implications of the erratum:
| Pagetable isolation between EL0 and higher level ELs prevents the | issue from occurring.
... and as per the workaround description quoted above, the workaround is only necessary "If pagetable isolation is disabled".
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/26xxx/CVE-2024-26670.json" }- References
-
- https://git.kernel.org/stable/c/58eb5c07f41704464b9acc09ab0707b6769db6c0
- https://git.kernel.org/stable/c/832dd634bd1b4e3bbe9f10b9c9ba5db6f6f2b97f
- https://git.kernel.org/stable/c/baa0aaac16432019651e0d60c41cd34a0c3c3477
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/26xxx/CVE-2024-26670.json
- https://nvd.nist.gov/vuln/detail/CVE-2024-26670
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced471470bc7052d28ce125901877dd10e4c048e513Fixed58eb5c07f41704464b9acc09ab0707b6769db6c0Fixedbaa0aaac16432019651e0d60c41cd34a0c3c3477Fixed832dd634bd1b4e3bbe9f10b9c9ba5db6f6f2b97f
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.1.57Fixed6.2
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.5.7Fixed6.6
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6e3ae2927b432a3b7c8374f14dbc1bd9ebe4372c
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced32b0a4ffcaea44a00a61e40c0d1bcc50362aee25