[Qemu-devel] [PATCH 04/25] s390x/mmu: Check table length and offset fields

[Jens Freimann]

From: Thomas Huth <address@hidden>

The ACSEs have a table length field and the region entries have
table length and offset fields which must be checked during
translation to see whether the given virtual address is really
covered by the translation table.

Signed-off-by: Thomas Huth <address@hidden>
Signed-off-by: Jens Freimann <address@hidden>
---
 target-s390x/cpu.h        |  1 +
 target-s390x/mmu_helper.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 95d0f3b..5563042 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -837,6 +837,7 @@ struct sysib_322 {
 #define _ASCE_TABLE_LENGTH      0x03      /* region table length              
*/
 
 #define _REGION_ENTRY_ORIGIN    ~0xfffULL /* region/segment table origin      
*/
+#define _REGION_ENTRY_TF        0xc0      /* region/segment table offset      
*/
 #define _REGION_ENTRY_INV       0x20      /* invalid region table entry       
*/
 #define _REGION_ENTRY_TYPE_MASK 0x0c      /* region/segment table type mask   
*/
 #define _REGION_ENTRY_TYPE_R1   0x0c      /* region first table type          
*/
diff --git a/target-s390x/mmu_helper.c b/target-s390x/mmu_helper.c
index 01d819e..d4087ba 100644
--- a/target-s390x/mmu_helper.c
+++ b/target-s390x/mmu_helper.c
@@ -171,6 +171,10 @@ static int mmu_translate_region(CPUS390XState *env, 
target_ulong vaddr,
 {
     CPUState *cs = CPU(s390_env_get_cpu(env));
     uint64_t origin, offs, new_entry;
+    const int pchks[4] = {
+        PGM_SEGMENT_TRANS, PGM_REG_THIRD_TRANS,
+        PGM_REG_SEC_TRANS, PGM_REG_FIRST_TRANS
+    };
 
     PTE_DPRINTF("%s: 0x%" PRIx64 "\n", __func__, entry);
 
@@ -201,6 +205,15 @@ static int mmu_translate_region(CPUS390XState *env, 
target_ulong vaddr,
                                      rw);
     }
 
+    /* Check region table offset and length */
+    offs = (vaddr >> (28 + 11 * (level - 4) / 4)) & 3;
+    if (offs < ((new_entry & _REGION_ENTRY_TF) >> 6)
+        || offs > (new_entry & _REGION_ENTRY_LENGTH)) {
+        DPRINTF("%s: invalid offset or len (%lx)\n", __func__, new_entry);
+        trigger_page_fault(env, vaddr, pchks[level / 4 - 1], asc, rw);
+        return -1;
+    }
+
     /* yet another region */
     return mmu_translate_region(env, vaddr, asc, new_entry, level - 4,
                                 raddr, flags, rw);
@@ -238,6 +251,10 @@ static int mmu_translate_asc(CPUS390XState *env, 
target_ulong vaddr,
     level = asce & _ASCE_TYPE_MASK;
     switch (level) {
     case _ASCE_TYPE_REGION1:
+        if ((vaddr >> 62) > (asce & _ASCE_TABLE_LENGTH)) {
+            trigger_page_fault(env, vaddr, PGM_REG_FIRST_TRANS, asc, rw);
+            return -1;
+        }
         break;
     case _ASCE_TYPE_REGION2:
         if (vaddr & 0xffe0000000000000ULL) {
@@ -246,6 +263,10 @@ static int mmu_translate_asc(CPUS390XState *env, 
target_ulong vaddr,
             trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
             return -1;
         }
+        if ((vaddr >> 51 & 3) > (asce & _ASCE_TABLE_LENGTH)) {
+            trigger_page_fault(env, vaddr, PGM_REG_SEC_TRANS, asc, rw);
+            return -1;
+        }
         break;
     case _ASCE_TYPE_REGION3:
         if (vaddr & 0xfffffc0000000000ULL) {
@@ -254,6 +275,10 @@ static int mmu_translate_asc(CPUS390XState *env, 
target_ulong vaddr,
             trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
             return -1;
         }
+        if ((vaddr >> 40 & 3) > (asce & _ASCE_TABLE_LENGTH)) {
+            trigger_page_fault(env, vaddr, PGM_REG_THIRD_TRANS, asc, rw);
+            return -1;
+        }
         break;
     case _ASCE_TYPE_SEGMENT:
         if (vaddr & 0xffffffff80000000ULL) {
@@ -262,6 +287,10 @@ static int mmu_translate_asc(CPUS390XState *env, 
target_ulong vaddr,
             trigger_page_fault(env, vaddr, PGM_TRANS_SPEC, asc, rw);
             return -1;
         }
+        if ((vaddr >> 29 & 3) > (asce & _ASCE_TABLE_LENGTH)) {
+            trigger_page_fault(env, vaddr, PGM_SEGMENT_TRANS, asc, rw);
+            return -1;
+        }
         break;
     }
 
-- 
2.1.4