mm: fix NULL ptr deref when walking hugepages

[android-x86/kernel.git] / fs / proc / task_mmu.c

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2d60492..7faaf2a 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -747,6 +747,8 @@ static void pte_to_pagemap_entry(pagemap_entry_t *pme, pte_t pte)
        else if (pte_present(pte))
                *pme = make_pme(PM_PFRAME(pte_pfn(pte))
                                | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
+       else
+               *pme = make_pme(PM_NOT_PRESENT);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -761,6 +763,8 @@ static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme,
        if (pmd_present(pmd))
                *pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset)
                                | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
+       else
+               *pme = make_pme(PM_NOT_PRESENT);
 }
 #else
 static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme,
@@ -780,7 +784,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 
        /* find the first VMA at or above 'addr' */
        vma = find_vma(walk->mm, addr);
-       if (pmd_trans_huge_lock(pmd, vma) == 1) {
+       if (vma && pmd_trans_huge_lock(pmd, vma) == 1) {
                for (; addr != end; addr += PAGE_SIZE) {
                        unsigned long offset;
 
@@ -801,8 +805,10 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 
                /* check to see if we've left 'vma' behind
                 * and need a new, higher one */
-               if (vma && (addr >= vma->vm_end))
+               if (vma && (addr >= vma->vm_end)) {
                        vma = find_vma(walk->mm, addr);
+                       pme = make_pme(PM_NOT_PRESENT);
+               }
 
                /* check that 'vma' actually covers this address,
                 * and that it isn't a huge page vma */
@@ -830,6 +836,8 @@ static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme,
        if (pte_present(pte))
                *pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset)
                                | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
+       else
+               *pme = make_pme(PM_NOT_PRESENT);
 }
 
 /* This function walks within one hugetlb entry in the single call */
@@ -839,7 +847,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 {
        struct pagemapread *pm = walk->private;
        int err = 0;
-       pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);
+       pagemap_entry_t pme;
 
        for (; addr != end; addr += PAGE_SIZE) {
                int offset = (addr & ~hmask) >> PAGE_SHIFT;