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ARM: fix get_user_pages_fast 

Ensure that get_user_pages_fast() is not able to access memory which
has been mapped with PROT_NONE.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Russell King 2017-10-25 11:04:14 +01:00
parent b9dd05c700
commit 1ee5e87f86
1 changed files with 12 additions and 0 deletions
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12
arch/arm/include/asm/pgtable.h
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@ -232,6 +232,18 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
#define pte_valid_user(pte) \
(pte_valid(pte) && pte_isset((pte), L_PTE_USER) && pte_young(pte))
static inline bool pte_access_permitted(pte_t pte, bool write)
{
pteval_t mask = L_PTE_PRESENT | L_PTE_USER;
pteval_t needed = mask;
if (write)
mask |= L_PTE_RDONLY;
return (pte_val(pte) & mask) == needed;
}
#define pte_access_permitted pte_access_permitted
#if __LINUX_ARM_ARCH__ < 6
static inline void __sync_icache_dcache(pte_t pteval)
{