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Philip Derrin authored
Currently, for ARM kernels with CONFIG_ARM_LPAE and CONFIG_STRICT_KERNEL_RWX enabled, the 2MiB pages mapping the kernel code and rodata are writable. They are marked read-only in a software bit (L_PMD_SECT_RDONLY) but the hardware read-only bit is not set (PMD_SECT_AP2). For user mappings, the logic that propagates the software bit to the hardware bit is in set_pmd_at(); but for the kernel, section_update() writes the PMDs directly, skipping this logic. The fix is to set PMD_SECT_AP2 for read-only sections in section_update(), at the same time as L_PMD_SECT_RDONLY. Fixes: 1e347922 ("ARM: 8275/1: mm: fix PMD_SECT_RDONLY undeclared compile error") Signed-off-by:
Philip Derrin <philip@cog.systems> Reported-by:
Neil Dick <neil@cog.systems> Tested-by:
Neil Dick <neil@cog.systems> Tested-by:
Laura Abbott <labbott@redhat.com> Reviewed-by:
Kees Cook <keescook@chromium.org> Cc: stable@vger.kernel.org Signed-off-by:
Russell King <rmk+kernel@armlinux.org.uk>
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