m68k: Do not set global share for non-kernel shared pages

If the SG bit is set in MMUTR the page is accessible for all
userspace processes (ignoring the ASID). So a process might randomly
access a page from a different process which had a shared page
(from shared memory) in its context.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

1 files changed, 5 insertions, 4 deletions

diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c
index babd5a97cdcb..875b800ef0dd 100644
--- a/arch/m68k/mm/mcfmmu.c
+++ b/arch/m68k/mm/mcfmmu.c
@@ -87,7 +87,7 @@ void __init paging_init(void)
 
 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
 {
-        unsigned long flags, mmuar;
+        unsigned long flags, mmuar, mmutr;
         struct mm_struct *mm;
         pgd_t *pgd;
         pmd_t *pmd;
@@ -137,9 +137,10 @@ int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
         if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
                 set_pte(pte, pte_wrprotect(*pte));
 
-        mmu_write(MMUTR, (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) |
-                (((int)(pte->pte) & (int)CF_PAGE_MMUTR_MASK)
-                >> CF_PAGE_MMUTR_SHIFT) | MMUTR_V);
+        mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
+        if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
+                mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
+        mmu_write(MMUTR, mmutr);
 
         mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
                 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);