From: Khalid Aziz khalid.aziz@oracle.com
[ Upstream commit 147d8622f2a26ef34beacc60e1ed8b66c2fa457f ]
When userspace calls mprotect() to enable ADI on an address range, do_mprotect_pkey() calls arch_validate_prot() to validate new protection flags. arch_validate_prot() for sparc looks at the first VMA associated with address range to verify if ADI can indeed be enabled on this address range. This has two issues - (1) Address range might cover multiple VMAs while arch_validate_prot() looks at only the first VMA, (2) arch_validate_prot() peeks at VMA without holding mmap lock which can result in race condition.
arch_validate_flags() from commit c462ac288f2c ("mm: Introduce arch_validate_flags()") allows for VMA flags to be validated for all VMAs that cover the address range given by user while holding mmap lock. This patch updates sparc code to move the VMA check from arch_validate_prot() to arch_validate_flags() to fix above two issues.
Suggested-by: Jann Horn jannh@google.com Suggested-by: Christoph Hellwig hch@infradead.org Suggested-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Khalid Aziz khalid.aziz@oracle.com Reviewed-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- arch/sparc/include/asm/mman.h | 54 +++++++++++++++++++---------------- 1 file changed, 29 insertions(+), 25 deletions(-)
diff --git a/arch/sparc/include/asm/mman.h b/arch/sparc/include/asm/mman.h index f94532f25db14..274217e7ed702 100644 --- a/arch/sparc/include/asm/mman.h +++ b/arch/sparc/include/asm/mman.h @@ -57,35 +57,39 @@ static inline int sparc_validate_prot(unsigned long prot, unsigned long addr) { if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_ADI)) return 0; - if (prot & PROT_ADI) { - if (!adi_capable()) - return 0; + return 1; +}
- if (addr) { - struct vm_area_struct *vma; +#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags) +/* arch_validate_flags() - Ensure combination of flags is valid for a + * VMA. + */ +static inline bool arch_validate_flags(unsigned long vm_flags) +{ + /* If ADI is being enabled on this VMA, check for ADI + * capability on the platform and ensure VMA is suitable + * for ADI + */ + if (vm_flags & VM_SPARC_ADI) { + if (!adi_capable()) + return false;
- vma = find_vma(current->mm, addr); - if (vma) { - /* ADI can not be enabled on PFN - * mapped pages - */ - if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) - return 0; + /* ADI can not be enabled on PFN mapped pages */ + if (vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) + return false;
- /* Mergeable pages can become unmergeable - * if ADI is enabled on them even if they - * have identical data on them. This can be - * because ADI enabled pages with identical - * data may still not have identical ADI - * tags on them. Disallow ADI on mergeable - * pages. - */ - if (vma->vm_flags & VM_MERGEABLE) - return 0; - } - } + /* Mergeable pages can become unmergeable + * if ADI is enabled on them even if they + * have identical data on them. This can be + * because ADI enabled pages with identical + * data may still not have identical ADI + * tags on them. Disallow ADI on mergeable + * pages. + */ + if (vm_flags & VM_MERGEABLE) + return false; } - return 1; + return true; } #endif /* CONFIG_SPARC64 */