CVE-2026-93256arm64: hibernate: mask DAIF before restoring hibernated kernel

Official description

In the Linux kernel, the following vulnerability has been resolved: arm64: hibernate: mask DAIF before restoring hibernated kernel The arm64 hibernate code manages the exception masking in an unsound way, leading to potential crashes and/or warnings during resume. When a hibernation image is saved in `swsusp_arch_suspend()`, all DAIF exceptions are masked (by virtue of `local_daif_save()`), and the suspended image is saved assuming that all DAIF exceptions will remain masked when the image is restored. When a hibernation image is resumed by `swsusp_arch_resume()`, only interrupts are masked (by virtue of `local_irq_disable()` in `resume_target_kernel()`). When pseudo-NMI is enabled the DAIF.IF bits will be clear, and regardless of pseudo-NMI the DAIF.DA bits will be clear. This means that there are two problems: (1) It is possible to take Debug, SError, or pseudo-NMI exceptions during the resume process. This is unsafe, as during the resume process both the old ane new kernels will tranisently be in an inconsistent state, and swsusp_arch_suspend_exit() won't retain an executable mapping of any exception vectors. Any exception taken here will be fatal and silent. (2) When re-entering the resumed kernel, some DAIF bits will be clear unexpectedly. This permits Debug, SError, or pseudo-NMI exceptions to be taken for a short period while the resumed kernel is not yet in a consistent state. This is detected by CONFIG_ARM64_DEBUG_PRIORITY_MASKING. Avoid these issues by masking all DAIF exceptions during resume.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/c9c671e9ab87b639720db8f7f8648bdf0f3bc8ec
• https://git.kernel.org/stable/c/099ad3edcef1d955d9f5d6aab16ae78ecdfd4cda
• https://git.kernel.org/stable/c/716c41bd476334afb943308be9ff2142e34461b7
• https://git.kernel.org/stable/c/5370853041a3cb53a125b77528586278f64b378b
• https://git.kernel.org/stable/c/290c5b0c9fc0c61fb1c41421ed2394f955206ea0
• https://git.kernel.org/stable/c/012823494e20c3cce622982ebd3fd6971be39ad2
• https://git.kernel.org/stable/c/d736ace2c491623c9ab5e73744085e93e9ae3ebe
• https://git.kernel.org/stable/c/684bde100117931f4c51c644a95f42f2dab041bc