linux-kernel - [PATCH v2 7/8] binder: fix memleak of proc->delivered

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Message-ID: <20240926233632.821189-8-cmllamas@google.com>
Date: Thu, 26 Sep 2024 23:36:18 +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 7/8] binder: fix memleak of proc->delivered_freeze

If a freeze notification is cleared with BC_CLEAR_FREEZE_NOTIFICATION
before calling binder_freeze_notification_done(), then it is detached
from its reference (e.g. ref->freeze) but the work remains queued in
proc->delivered_freeze. This leads to a memory leak when the process
exits as any pending entries in proc->delivered_freeze are not freed:

  unreferenced object 0xffff38e8cfa36180 (size 64):
    comm "binder-util", pid 655, jiffies 4294936641
    hex dump (first 32 bytes):
      b8 e9 9e c8 e8 38 ff ff b8 e9 9e c8 e8 38 ff ff  .....8.......8..
      0b 00 00 00 00 00 00 00 3c 1f 4b 00 00 00 00 00  ........<.K.....
    backtrace (crc 95983b32):
      [<000000000d0582cf>] kmemleak_alloc+0x34/0x40
      [<000000009c99a513>] __kmalloc_cache_noprof+0x208/0x280
      [<00000000313b1704>] binder_thread_write+0xdec/0x439c
      [<000000000cbd33bb>] binder_ioctl+0x1b68/0x22cc
      [<000000002bbedeeb>] __arm64_sys_ioctl+0x124/0x190
      [<00000000b439adee>] invoke_syscall+0x6c/0x254
      [<00000000173558fc>] el0_svc_common.constprop.0+0xac/0x230
      [<0000000084f72311>] do_el0_svc+0x40/0x58
      [<000000008b872457>] el0_svc+0x38/0x78
      [<00000000ee778653>] el0t_64_sync_handler+0x120/0x12c
      [<00000000a8ec61bf>] el0t_64_sync+0x190/0x194

This patch fixes the leak by ensuring that any pending entries in
proc->delivered_freeze are freed during binder_deferred_release().

Fixes: d579b04a52a1 ("binder: frozen notification")
Cc: stable@...r.kernel.org
Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
---
 drivers/android/binder.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 415fc9759249..7c09b5e38e32 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -5155,6 +5155,16 @@ static void binder_release_work(struct binder_proc *proc,
 		} break;
 		case BINDER_WORK_NODE:
 			break;
+		case BINDER_WORK_CLEAR_FREEZE_NOTIFICATION: {
+			struct binder_ref_freeze *freeze;
+
+			freeze = container_of(w, struct binder_ref_freeze, work);
+			binder_debug(BINDER_DEBUG_DEAD_TRANSACTION,
+				     "undelivered freeze notification, %016llx\n",
+				     (u64)freeze->cookie);
+			kfree(freeze);
+			binder_stats_deleted(BINDER_STAT_FREEZE);
+		} break;
 		default:
 			pr_err("unexpected work type, %d, not freed\n",
 			       wtype);
@@ -6273,6 +6283,7 @@ static void binder_deferred_release(struct binder_proc *proc)
 
 	binder_release_work(proc, &proc->todo);
 	binder_release_work(proc, &proc->delivered_death);
+	binder_release_work(proc, &proc->delivered_freeze);
 
 	binder_debug(BINDER_DEBUG_OPEN_CLOSE,
 		     "%s: %d threads %d, nodes %d (ref %d), refs %d, active transactions %d\n",
-- 
2.46.1.824.gd892dcdcdd-goog