4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ard Biesheuvel ard.biesheuvel@linaro.org
commit 753e8abc36b2c966caea075db0c845563c8a19bf upstream.
The routine pgattr_change_is_safe() was extended in commit 4e6020565596 ("arm64: mm: Permit transitioning from Global to Non-Global without BBM") to permit changing the nG attribute from not set to set, but did so in a way that inadvertently disallows such changes if other permitted attribute changes take place at the same time. So update the code to take this into account.
Fixes: 4e6020565596 ("arm64: mm: Permit transitioning from Global to ...") Cc: stable@vger.kernel.org # 4.14.x- Acked-by: Mark Rutland mark.rutland@arm.com Reviewed-by: Marc Zyngier marc.zyngier@arm.com Acked-by: Will Deacon will.deacon@arm.com Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arm64/mm/mmu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -107,7 +107,7 @@ static bool pgattr_change_is_safe(u64 ol * The following mapping attributes may be updated in live * kernel mappings without the need for break-before-make. */ - static const pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE; + static const pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG;
/* creating or taking down mappings is always safe */ if (old == 0 || new == 0) @@ -117,9 +117,9 @@ static bool pgattr_change_is_safe(u64 ol if ((old | new) & PTE_CONT) return false;
- /* Transitioning from Global to Non-Global is safe */ - if (((old ^ new) == PTE_NG) && (new & PTE_NG)) - return true; + /* Transitioning from Non-Global to Global is unsafe */ + if (old & ~new & PTE_NG) + return false;
return ((old ^ new) & ~mask) == 0; }