From: Arve Hjønnevåg <arve@xxxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
commit 0a3ffab93fe52530602fe47cd74802cffdb19c05 upstream.
Prevent using a binder_ref with only weak references where a strong
reference is required.
Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx>
Signed-off-by: Martijn Coenen <maco@xxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/staging/android/binder.c | 30 +++++++++++++++++++++---------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 69fd236345cb..8a436dae9b77 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -994,7 +994,7 @@ 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)
+ u32 desc, bool need_strong_ref)
{
struct rb_node *n = proc->refs_by_desc.rb_node;
struct binder_ref *ref;
@@ -1002,12 +1002,16 @@ 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;
}
@@ -1270,7 +1274,10 @@ 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;
+
+ ref = binder_get_ref(proc, fp->handle,
+ fp->type == BINDER_TYPE_HANDLE);
if (ref == NULL) {
pr_err("transaction release %d bad handle %d\n",
debug_id, fp->handle);
@@ -1362,7 +1369,7 @@ static void binder_transaction(struct binder_proc *proc,
} else {
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);
@@ -1546,7 +1553,10 @@ 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;
+
+ 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",
proc->pid,
@@ -1739,7 +1749,9 @@ int binder_thread_write(struct binder_proc *proc, struct binder_thread *thread,
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);
@@ -1934,7 +1946,7 @@ int binder_thread_write(struct binder_proc *proc, struct binder_thread *thread,
if (get_user(cookie, (void __user * __user *)ptr))
return -EFAULT;
ptr += sizeof(void *);
- 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,
--
2.10.2
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