From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Marc Zyngier , Will Deacon , Ard Biesheuvel , Catalin Marinas Subject: [PATCH 4.15 054/146] arm64: mm: fix thinko in non-global page table attribute check Date: Tue, 13 Mar 2018 16:23:41 +0100 Message-Id: <20180313152324.816712250@linuxfoundation.org> In-Reply-To: <20180313152320.439085687@linuxfoundation.org> References: <20180313152320.439085687@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ard Biesheuvel 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: # 4.14.x- Acked-by: Mark Rutland Reviewed-by: Marc Zyngier Acked-by: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- 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; }