[Qemu-devel] [PATCH] target-s390x: Only access allocated storage keys

[Qemu-devel] [PATCH] target-s390x: Only access allocated storage keys

[Alexander Graf]

We allocate ram_size / PAGE_SIZE storage keys, so we need to make sure that
we only access that many. Unfortunately the code can overrun this array by
one, potentially overwriting unrelated memory.

Fix it by limiting storage keys to their scope.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 target-s390x/mmu_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-s390x/mmu_helper.c b/target-s390x/mmu_helper.c
index e8dcd0c..815ff42 100644
--- a/target-s390x/mmu_helper.c
+++ b/target-s390x/mmu_helper.c
@@ -358,7 +358,7 @@ int mmu_translate(CPUS390XState *env, target_ulong vaddr, int rw, uint64_t asc,
     /* Convert real address -> absolute address */
     *raddr = mmu_real2abs(env, *raddr);
 
-    if (*raddr <= ram_size) {
+    if (*raddr < ram_size) {
         sk = &env->storage_keys[*raddr / TARGET_PAGE_SIZE];
         if (*flags & PAGE_READ) {
             *sk |= SK_R;
-- 
2.2.1

Re: [Qemu-devel] [PATCH] target-s390x: Only access allocated storage keys

[Aurelien Jarno]

On 2015-06-04 00:52, Alexander Graf wrote:
> We allocate ram_size / PAGE_SIZE storage keys, so we need to make sure that
> we only access that many. Unfortunately the code can overrun this array by
> one, potentially overwriting unrelated memory.
> 
> Fix it by limiting storage keys to their scope.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  target-s390x/mmu_helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target-s390x/mmu_helper.c b/target-s390x/mmu_helper.c
> index e8dcd0c..815ff42 100644
> --- a/target-s390x/mmu_helper.c
> +++ b/target-s390x/mmu_helper.c
> @@ -358,7 +358,7 @@ int mmu_translate(CPUS390XState *env, target_ulong vaddr, int rw, uint64_t asc,
>      /* Convert real address -> absolute address */
>      *raddr = mmu_real2abs(env, *raddr);
>  
> -    if (*raddr <= ram_size) {
> +    if (*raddr < ram_size) {
>          sk = &env->storage_keys[*raddr / TARGET_PAGE_SIZE];
>          if (*flags & PAGE_READ) {
>              *sk |= SK_R;

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net