cbcvebase.
CVE-2024-26670
published 2024-04-02

CVE-2024-26670: In the Linux kernel, the following vulnerability has been resolved: arm64: entry: fix ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD Currently the…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.22%
13.3th percentile
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_

Affected

13 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.6.15-1 (forky)linux 6.6.15-1 (forky)
linuxlinux
linuxlinux
linuxlinux
linuxlinux>= 471470bc7052d28ce125901877dd10e4c048e513 < 58eb5c07f41704464b9acc09ab0707b6769db6c058eb5c07f41704464b9acc09ab0707b6769db6c0
linuxlinux>= 471470bc7052d28ce125901877dd10e4c048e513 < baa0aaac16432019651e0d60c41cd34a0c3c3477baa0aaac16432019651e0d60c41cd34a0c3c3477
linuxlinux>= 471470bc7052d28ce125901877dd10e4c048e513 < 832dd634bd1b4e3bbe9f10b9c9ba5db6f6f2b97f832dd634bd1b4e3bbe9f10b9c9ba5db6f6f2b97f
linuxlinux>= 6.1.57 < 6.26.2
linuxlinux>= 6.5.7 < 6.66.6
linuxlinux_kernel>= 0 < 6.6.15-16.6.15-1
linuxlinux_kernel>= 0 < 6.6.15-16.6.15-1
linuxlinux_kernel>= 6.6 < 6.6.156.6.15
linuxlinux_kernel>= 6.7 < 6.7.36.7.3

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.5HIGH
vendor_ubuntu6.5MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
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