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Date: Mon,  6 Apr 2020 17:20:42 +0300
From: Lev Olshvang <levonshe@...il.com>
To: arnd@...db.de
Cc: kernel-hardening@...ts.openwall.com,
	Lev Olshvang <levonshe@...il.com>
Subject: [RFC PATCH 2/5] Prevent write to read-only pages from another process

Signed-off-by: Lev Olshvang <levonshe@...il.com>
---
 arch/unicore32/include/asm/mmu_context.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/unicore32/include/asm/mmu_context.h b/arch/unicore32/include/asm/mmu_context.h
index 388c0c811c68..caf240b8a748 100644
--- a/arch/unicore32/include/asm/mmu_context.h
+++ b/arch/unicore32/include/asm/mmu_context.h
@@ -92,7 +92,12 @@ static inline void arch_unmap(struct mm_struct *mm,
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {
+#ifdef CONFIG_PROTECT_READONLY_USER_MEMORY
+	/* Forbid write to PROT_READ pages of foreign process */
+	if (write && foreign && (!(vma->vm_flags & VM_WRITE)))
+		return false;
+#endif
 	/* by default, allow everything */
 	return true;
 }
-#endif
+#endif /*__UNICORE_MMU_CONTEXT_H__*/
--
2.17.1

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