[PATCH 0/2] STRICT_KERNEL_RWX weakened on ARM by CONFIG_ARM_LPAE=y

[Florian Fainelli]

On 11/08/2017 04:41 PM, Philip Derrin wrote:
> Hi,
> 
> This patch series fixes a bug which makes CONFIG_STRICT_KERNEL_RWX ineffective
> when CONFIG_ARM_LPAE is enabled. Specifically, the kernel text and rodata are
> mapped writeable. This has been the case since DEBUG_RODATA for ARM was first
> merged in 3.19.
> 
> The cause was an incorrect conflict resolution in 1e3479225acb ("ARM: 8275/1:
> mm: fix PMD_SECT_RDONLY undeclared compile error") between the commit that
> implemented DEBUG_RODATA, 80d6b0c2eed2 ("ARM: mm: allow text and rodata
> sections to be read-only"), and another that moved the LPAE read-only bit into
> a software bit, ded947798469 ("ARM: 8109/1: mm: Modify pte_write and pmd_write
> logic for LPAE").
> 
> The incorrect mappings were not apparent in the debugfs kernel_page_tables
> dump because that was checking only the software RO bit, not the hardware RO
> bit.

FWIW, on an ARCH_BRCMSTB system with ARM_LPAE=y:

Tested-by: Florian Fainelli <f.fainelli at gmail.com>
-- 
Florian