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-rw-r--r--drivers/android/binder.c104
-rw-r--r--drivers/android/binder_alloc.c24
-rw-r--r--drivers/android/binder_alloc.h1
3 files changed, 77 insertions, 52 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index ab34239a76ee..fddf76ef5bd6 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2582,6 +2582,48 @@ static bool binder_proc_transaction(struct binder_transaction *t,
return true;
}
+/**
+ * binder_get_node_refs_for_txn() - Get required refs on node for txn
+ * @node: struct binder_node for which to get refs
+ * @proc: returns @node->proc if valid
+ * @error: if no @proc then returns BR_DEAD_REPLY
+ *
+ * User-space normally keeps the node alive when creating a transaction
+ * since it has a reference to the target. The local strong ref keeps it
+ * alive if the sending process dies before the target process processes
+ * the transaction. If the source process is malicious or has a reference
+ * counting bug, relying on the local strong ref can fail.
+ *
+ * Since user-space can cause the local strong ref to go away, we also take
+ * a tmpref on the node to ensure it survives while we are constructing
+ * the transaction. We also need a tmpref on the proc while we are
+ * constructing the transaction, so we take that here as well.
+ *
+ * Return: The target_node with refs taken or NULL if no @node->proc is NULL.
+ * Also sets @proc if valid. If the @node->proc is NULL indicating that the
+ * target proc has died, @error is set to BR_DEAD_REPLY
+ */
+static struct binder_node *binder_get_node_refs_for_txn(
+ struct binder_node *node,
+ struct binder_proc **procp,
+ uint32_t *error)
+{
+ struct binder_node *target_node = NULL;
+
+ binder_node_inner_lock(node);
+ if (node->proc) {
+ target_node = node;
+ binder_inc_node_nilocked(node, 1, 0, NULL);
+ binder_inc_node_tmpref_ilocked(node);
+ node->proc->tmp_ref++;
+ *procp = node->proc;
+ } else
+ *error = BR_DEAD_REPLY;
+ binder_node_inner_unlock(node);
+
+ return target_node;
+}
+
static void binder_transaction(struct binder_proc *proc,
struct binder_thread *thread,
struct binder_transaction_data *tr, int reply,
@@ -2685,43 +2727,35 @@ static void binder_transaction(struct binder_proc *proc,
ref = binder_get_ref_olocked(proc, tr->target.handle,
true);
if (ref) {
- binder_inc_node(ref->node, 1, 0, NULL);
- target_node = ref->node;
- }
- binder_proc_unlock(proc);
- if (target_node == NULL) {
+ target_node = binder_get_node_refs_for_txn(
+ ref->node, &target_proc,
+ &return_error);
+ } else {
binder_user_error("%d:%d got transaction to invalid handle\n",
- proc->pid, thread->pid);
+ proc->pid, thread->pid);
return_error = BR_FAILED_REPLY;
- return_error_param = -EINVAL;
- return_error_line = __LINE__;
- goto err_invalid_target_handle;
}
+ binder_proc_unlock(proc);
} else {
mutex_lock(&context->context_mgr_node_lock);
target_node = context->binder_context_mgr_node;
- if (target_node == NULL) {
+ if (target_node)
+ target_node = binder_get_node_refs_for_txn(
+ target_node, &target_proc,
+ &return_error);
+ else
return_error = BR_DEAD_REPLY;
- mutex_unlock(&context->context_mgr_node_lock);
- return_error_line = __LINE__;
- goto err_no_context_mgr_node;
- }
- binder_inc_node(target_node, 1, 0, NULL);
mutex_unlock(&context->context_mgr_node_lock);
}
- e->to_node = target_node->debug_id;
- binder_node_lock(target_node);
- target_proc = target_node->proc;
- if (target_proc == NULL) {
- binder_node_unlock(target_node);
- return_error = BR_DEAD_REPLY;
+ if (!target_node) {
+ /*
+ * return_error is set above
+ */
+ return_error_param = -EINVAL;
return_error_line = __LINE__;
goto err_dead_binder;
}
- binder_inner_proc_lock(target_proc);
- target_proc->tmp_ref++;
- binder_inner_proc_unlock(target_proc);
- binder_node_unlock(target_node);
+ e->to_node = target_node->debug_id;
if (security_binder_transaction(proc->tsk,
target_proc->tsk) < 0) {
return_error = BR_FAILED_REPLY;
@@ -3071,6 +3105,8 @@ static void binder_transaction(struct binder_proc *proc,
if (target_thread)
binder_thread_dec_tmpref(target_thread);
binder_proc_dec_tmpref(target_proc);
+ if (target_node)
+ binder_dec_node_tmpref(target_node);
/*
* write barrier to synchronize with initialization
* of log entry
@@ -3090,6 +3126,8 @@ err_bad_parent:
err_copy_data_failed:
trace_binder_transaction_failed_buffer_release(t->buffer);
binder_transaction_buffer_release(target_proc, t->buffer, offp);
+ if (target_node)
+ binder_dec_node_tmpref(target_node);
target_node = NULL;
t->buffer->transaction = NULL;
binder_alloc_free_buf(&target_proc->alloc, t->buffer);
@@ -3104,13 +3142,14 @@ err_bad_call_stack:
err_empty_call_stack:
err_dead_binder:
err_invalid_target_handle:
-err_no_context_mgr_node:
if (target_thread)
binder_thread_dec_tmpref(target_thread);
if (target_proc)
binder_proc_dec_tmpref(target_proc);
- if (target_node)
+ if (target_node) {
binder_dec_node(target_node, 1, 0);
+ binder_dec_node_tmpref(target_node);
+ }
binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
"%d:%d transaction failed %d/%d, size %lld-%lld line %d\n",
@@ -3623,12 +3662,6 @@ static void binder_stat_br(struct binder_proc *proc,
}
}
-static int binder_has_thread_work(struct binder_thread *thread)
-{
- return !binder_worklist_empty(thread->proc, &thread->todo) ||
- thread->looper_need_return;
-}
-
static int binder_put_node_cmd(struct binder_proc *proc,
struct binder_thread *thread,
void __user **ptrp,
@@ -4258,12 +4291,9 @@ static unsigned int binder_poll(struct file *filp,
binder_inner_proc_unlock(thread->proc);
- if (binder_has_work(thread, wait_for_proc_work))
- return POLLIN;
-
poll_wait(filp, &thread->wait, wait);
- if (binder_has_thread_work(thread))
+ if (binder_has_work(thread, wait_for_proc_work))
return POLLIN;
return 0;
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 064f5e31ec55..c2819a3d58a6 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -215,17 +215,12 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
}
}
- if (!vma && need_mm)
- mm = get_task_mm(alloc->tsk);
+ if (!vma && need_mm && mmget_not_zero(alloc->vma_vm_mm))
+ mm = alloc->vma_vm_mm;
if (mm) {
down_write(&mm->mmap_sem);
vma = alloc->vma;
- if (vma && mm != alloc->vma_vm_mm) {
- pr_err("%d: vma mm and task mm mismatch\n",
- alloc->pid);
- vma = NULL;
- }
}
if (!vma && need_mm) {
@@ -565,7 +560,7 @@ static void binder_delete_free_buffer(struct binder_alloc *alloc,
binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
"%d: merge free, buffer %pK do not share page with %pK or %pK\n",
alloc->pid, buffer->data,
- prev->data, next->data);
+ prev->data, next ? next->data : NULL);
binder_update_page_range(alloc, 0, buffer_start_page(buffer),
buffer_start_page(buffer) + PAGE_SIZE,
NULL);
@@ -720,6 +715,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
barrier();
alloc->vma = vma;
alloc->vma_vm_mm = vma->vm_mm;
+ mmgrab(alloc->vma_vm_mm);
return 0;
@@ -795,6 +791,8 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
vfree(alloc->buffer);
}
mutex_unlock(&alloc->mutex);
+ if (alloc->vma_vm_mm)
+ mmdrop(alloc->vma_vm_mm);
binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
"%s: %d buffers %d, pages %d\n",
@@ -889,7 +887,6 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
void binder_alloc_vma_close(struct binder_alloc *alloc)
{
WRITE_ONCE(alloc->vma, NULL);
- WRITE_ONCE(alloc->vma_vm_mm, NULL);
}
/**
@@ -926,9 +923,9 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
vma = alloc->vma;
if (vma) {
- mm = get_task_mm(alloc->tsk);
- if (!mm)
- goto err_get_task_mm_failed;
+ if (!mmget_not_zero(alloc->vma_vm_mm))
+ goto err_mmget;
+ mm = alloc->vma_vm_mm;
if (!down_write_trylock(&mm->mmap_sem))
goto err_down_write_mmap_sem_failed;
}
@@ -963,7 +960,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
err_down_write_mmap_sem_failed:
mmput_async(mm);
-err_get_task_mm_failed:
+err_mmget:
err_page_already_freed:
mutex_unlock(&alloc->mutex);
err_get_alloc_mutex_failed:
@@ -1002,7 +999,6 @@ struct shrinker binder_shrinker = {
*/
void binder_alloc_init(struct binder_alloc *alloc)
{
- alloc->tsk = current->group_leader;
alloc->pid = current->group_leader->pid;
mutex_init(&alloc->mutex);
INIT_LIST_HEAD(&alloc->buffers);
diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index a3a3602c689c..2dd33b6df104 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -100,7 +100,6 @@ struct binder_lru_page {
*/
struct binder_alloc {
struct mutex mutex;
- struct task_struct *tsk;
struct vm_area_struct *vma;
struct mm_struct *vma_vm_mm;
void *buffer;
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-27 11:28:07 +0000