ANDROID: binder: Add strong ref checks
Prevent using a binder_ref with only weak references where a strong
reference is required.
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 562af94..3681759 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -1002,7 +1002,7 @@
static struct binder_ref *binder_get_ref(struct binder_proc *proc,
- uint32_t desc)
+ u32 desc, bool need_strong_ref)
{
struct rb_node *n = proc->refs_by_desc.rb_node;
struct binder_ref *ref;
@@ -1010,12 +1010,16 @@
while (n) {
ref = rb_entry(n, struct binder_ref, rb_node_desc);
- if (desc < ref->desc)
+ if (desc < ref->desc) {
n = n->rb_left;
- else if (desc > ref->desc)
+ } else if (desc > ref->desc) {
n = n->rb_right;
- else
+ } else if (need_strong_ref && !ref->strong) {
+ binder_user_error("tried to use weak ref as strong ref\n");
+ return NULL;
+ } else {
return ref;
+ }
}
return NULL;
}
@@ -1285,7 +1289,10 @@
} break;
case BINDER_TYPE_HANDLE:
case BINDER_TYPE_WEAK_HANDLE: {
- struct binder_ref *ref = binder_get_ref(proc, fp->handle);
+ struct binder_ref *ref;
+
+ ref = binder_get_ref(proc, fp->handle,
+ fp->type == BINDER_TYPE_HANDLE);
if (ref == NULL) {
pr_err("transaction release %d bad handle %d\n",
@@ -1380,7 +1387,7 @@
if (tr->target.handle) {
struct binder_ref *ref;
- ref = binder_get_ref(proc, tr->target.handle);
+ ref = binder_get_ref(proc, tr->target.handle, true);
if (ref == NULL) {
binder_user_error("%d:%d got transaction to invalid handle\n",
proc->pid, thread->pid);
@@ -1589,7 +1596,10 @@
} break;
case BINDER_TYPE_HANDLE:
case BINDER_TYPE_WEAK_HANDLE: {
- struct binder_ref *ref = binder_get_ref(proc, fp->handle);
+ struct binder_ref *ref;
+
+ ref = binder_get_ref(proc, fp->handle,
+ fp->type == BINDER_TYPE_HANDLE);
if (ref == NULL) {
binder_user_error("%d:%d got transaction with invalid handle, %d\n",
@@ -1800,7 +1810,9 @@
ref->desc);
}
} else
- ref = binder_get_ref(proc, target);
+ ref = binder_get_ref(proc, target,
+ cmd == BC_ACQUIRE ||
+ cmd == BC_RELEASE);
if (ref == NULL) {
binder_user_error("%d:%d refcount change on invalid ref %d\n",
proc->pid, thread->pid, target);
@@ -1996,7 +2008,7 @@
if (get_user(cookie, (binder_uintptr_t __user *)ptr))
return -EFAULT;
ptr += sizeof(binder_uintptr_t);
- ref = binder_get_ref(proc, target);
+ ref = binder_get_ref(proc, target, false);
if (ref == NULL) {
binder_user_error("%d:%d %s invalid ref %d\n",
proc->pid, thread->pid,