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authorHeiko Carstens <heiko.carstens@de.ibm.com>2012-10-01 16:18:46 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2012-10-09 14:16:57 +0200
commit5b1ba9e30cf0e259450da19189811eb140733f83 (patch)
tree033759c49f3159e9514e8b08282e41977477064c /arch/s390
parent378b1e7a80a59325ca1036e892462db728126f84 (diff)
s390/mm,pageattr: add more page table walk sanity checks
The current page table walk code in pageattr.c only checks for large pages while walking the kernel page table, but happily assumes that everything else is just fine. Add more checks so we never access invalid memory regions. Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/mm/pageattr.c37
1 files changed, 25 insertions, 12 deletions
diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index 0f33bab3e98..b56953dd95f 100644
--- a/arch/s390/mm/pageattr.c
+++ b/arch/s390/mm/pageattr.c
@@ -8,25 +8,38 @@
#include <asm/cacheflush.h>
#include <asm/pgtable.h>
+static pte_t *walk_page_table(unsigned long addr)
+{
+ pgd_t *pgdp;
+ pud_t *pudp;
+ pmd_t *pmdp;
+ pte_t *ptep;
+
+ pgdp = pgd_offset_k(addr);
+ if (pgd_none(*pgdp))
+ return NULL;
+ pudp = pud_offset(pgdp, addr);
+ if (pud_none(*pudp))
+ return NULL;
+ pmdp = pmd_offset(pudp, addr);
+ if (pmd_none(*pmdp) || pmd_large(*pmdp))
+ return NULL;
+ ptep = pte_offset_kernel(pmdp, addr);
+ if (pte_none(*ptep))
+ return NULL;
+ return ptep;
+}
+
static void change_page_attr(unsigned long addr, int numpages,
pte_t (*set) (pte_t))
{
pte_t *ptep, pte;
- pmd_t *pmdp;
- pud_t *pudp;
- pgd_t *pgdp;
int i;
for (i = 0; i < numpages; i++) {
- pgdp = pgd_offset(&init_mm, addr);
- pudp = pud_offset(pgdp, addr);
- pmdp = pmd_offset(pudp, addr);
- if (pmd_large(*pmdp)) {
- WARN_ON_ONCE(1);
- continue;
- }
- ptep = pte_offset_kernel(pmdp, addr);
-
+ ptep = walk_page_table(addr);
+ if (WARN_ON_ONCE(!ptep))
+ break;
pte = *ptep;
pte = set(pte);
__ptep_ipte(addr, ptep);