linux-kernel - [PATCH v2 6/8] binder: allow freeze notification for dead nodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240926233632.821189-7-cmllamas@google.com>
Date: Thu, 26 Sep 2024 23:36:17 +0000
From: Carlos Llamas <cmllamas@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	"Arve Hjønnevåg" <arve@...roid.com>, Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>, 
	Joel Fernandes <joel@...lfernandes.org>, Christian Brauner <brauner@...nel.org>, 
	Carlos Llamas <cmllamas@...gle.com>, Suren Baghdasaryan <surenb@...gle.com>, 
	Yu-Ting Tseng <yutingtseng@...gle.com>
Cc: linux-kernel@...r.kernel.org, kernel-team@...roid.com, 
	Alice Ryhl <aliceryhl@...gle.com>, stable@...r.kernel.org
Subject: [PATCH v2 6/8] binder: allow freeze notification for dead nodes

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: d579b04a52a1 ("binder: frozen notification")
Cc: stable@...r.kernel.org
Suggested-by: Alice Ryhl <aliceryhl@...gle.com>
Link: https://lore.kernel.org/all/CAH5fLghapZJ4PbbkC8V5A6Zay-_sgTzwVpwqk6RWWUNKKyJC_Q@mail.gmail.com/ [1]
Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
---
 drivers/android/binder.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 73dc6cbc1681..415fc9759249 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -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);
-- 
2.46.1.824.gd892dcdcdd-goog