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binder: allow freeze notification for dead nodes

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commit ca63c66935 upstream.

Alice points out that binder_request_freeze_notification() should not
return EINVAL when the relevant node is dead [1]. The node can die at
any point even if the user input is valid. Instead, allow the request
to be allocated but skip the initial notification for dead nodes. This
avoids propagating unnecessary errors back to userspace.

Fixes: d579b04a52 ("binder: frozen notification")
Cc: stable@vger.kernel.org
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/all/CAH5fLghapZJ4PbbkC8V5A6Zay-_sgTzwVpwqk6RWWUNKKyJC_Q@mail.gmail.com/ [1]
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20240926233632.821189-7-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Carlos Llamas
2024-09-26 23:36:17 +00:00
committed by Greg Kroah-Hartman
parent 648c92b1a8
commit f3cf682d3a
1 changed files with 13 additions and 15 deletions
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drivers/android/binder.c
+13 -15
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@@ -3856,7 +3856,6 @@ binder_request_freeze_notification(struct binder_proc *proc,
{
struct binder_ref_freeze *freeze;
struct binder_ref *ref;
bool is_frozen;
freeze = kzalloc(sizeof(*freeze), GFP_KERNEL);
if (!freeze)
@@ -3872,32 +3871,31 @@ binder_request_freeze_notification(struct binder_proc *proc,
}
binder_node_lock(ref->node);
if (ref->freeze || !ref->node->proc) {
binder_user_error("%d:%d invalid BC_REQUEST_FREEZE_NOTIFICATION %s\n",
proc->pid, thread->pid,
ref->freeze ? "already set" : "dead node");
if (ref->freeze) {
binder_user_error("%d:%d BC_REQUEST_FREEZE_NOTIFICATION already set\n",
proc->pid, thread->pid);
binder_node_unlock(ref->node);
binder_proc_unlock(proc);
kfree(freeze);
return -EINVAL;
}
binder_inner_proc_lock(ref->node->proc);
is_frozen = ref->node->proc->is_frozen;
binder_inner_proc_unlock(ref->node->proc);
binder_stats_created(BINDER_STAT_FREEZE);
INIT_LIST_HEAD(&freeze->work.entry);
freeze->cookie = handle_cookie->cookie;
freeze->work.type = BINDER_WORK_FROZEN_BINDER;
freeze->is_frozen = is_frozen;
ref->freeze = freeze;
binder_inner_proc_lock(proc);
binder_enqueue_work_ilocked(&ref->freeze->work, &proc->todo);
binder_wakeup_proc_ilocked(proc);
binder_inner_proc_unlock(proc);
if (ref->node->proc) {
binder_inner_proc_lock(ref->node->proc);
freeze->is_frozen = ref->node->proc->is_frozen;
binder_inner_proc_unlock(ref->node->proc);
binder_inner_proc_lock(proc);
binder_enqueue_work_ilocked(&freeze->work, &proc->todo);
binder_wakeup_proc_ilocked(proc);
binder_inner_proc_unlock(proc);
}
binder_node_unlock(ref->node);
binder_proc_unlock(proc);