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Commit 4581a896 authored by Arve Hjønnevåg's avatar Arve Hjønnevåg Committed by Amit Pundir
Browse files

ANDROID: binder: Add strong ref checks 



Prevent using a binder_ref with only weak references where a strong
reference is required.

BUG: 30445380
Change-Id: I66c15b066808f28bd27bfe50fd0e03ff45a09fca
Signed-off-by: default avatarArve Hjønnevåg <arve@android.com>
parent 2320e1e8

drivers/android/binder.c

+17 −9
Original line number Diff line number Diff line
@@ -1002,7 +1002,7 @@ static int binder_dec_node(struct binder_node *node, int strong, int internal) 




static struct binder_ref *binder_get_ref(struct binder_proc *proc,

					 uint32_t desc)

					 uint32_t desc, bool need_strong_ref)

{

	struct rb_node *n = proc->refs_by_desc.rb_node;

	struct binder_ref *ref;
@@ -1010,13 +1010,17 @@ static struct binder_ref *binder_get_ref(struct binder_proc *proc, 
	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 +1289,8 @@ static void binder_transaction_buffer_release(struct binder_proc *proc, 
		} break;

		case BINDER_TYPE_HANDLE:

		case BINDER_TYPE_WEAK_HANDLE: {

			struct binder_ref *ref = binder_get_ref(proc, fp->handle);

			struct binder_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 +1385,7 @@ static void binder_transaction(struct binder_proc *proc, 
		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 +1594,8 @@ static void binder_transaction(struct binder_proc *proc, 
		} break;

		case BINDER_TYPE_HANDLE:

		case BINDER_TYPE_WEAK_HANDLE: {

			struct binder_ref *ref = binder_get_ref(proc, fp->handle);

			struct binder_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 +1806,9 @@ static int binder_thread_write(struct binder_proc *proc, 
						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 +2004,7 @@ static int binder_thread_write(struct binder_proc *proc, 
			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,