linux-kernel - [PATCH] binder: don't use %pK through printk

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Message-Id: <20260107-restricted-pointers-binder-v1-1-181018bf3812@linutronix.de>
Date: Wed, 07 Jan 2026 15:29:50 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Arve Hjønnevåg <arve@...roid.com>, 
 Todd Kjos <tkjos@...roid.com>, Christian Brauner <brauner@...nel.org>, 
 Carlos Llamas <cmllamas@...gle.com>, Alice Ryhl <aliceryhl@...gle.com>
Cc: linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH] binder: don't use %pK through printk

In the past %pK was preferable to %p as it would not leak raw pointer
values into the kernel log. Since commit ad67b74d2469 ("printk: hash
addresses printed with %p") the regular %p has been improved to avoid
this issue. Furthermore, restricted pointers ("%pK") were never meant
to be used through printk(). They can still unintentionally leak raw
pointers or acquire sleeping locks in atomic contexts.

Switch to the regular pointer formatting which is safer and
easier to reason about.

There are still a few users of %pK left, but these use it through
seq_file, for which its usage is safe.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 drivers/android/binder.c       | 2 +-
 drivers/android/binder_alloc.c | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 535fc881c8da..adde1e40cccd 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -4510,7 +4510,7 @@ static int binder_thread_write(struct binder_proc *proc,
 				}
 			}
 			binder_debug(BINDER_DEBUG_DEAD_BINDER,
-				     "%d:%d BC_DEAD_BINDER_DONE %016llx found %pK\n",
+				     "%d:%d BC_DEAD_BINDER_DONE %016llx found %p\n",
 				     proc->pid, thread->pid, (u64)cookie,
 				     death);
 			if (death == NULL) {
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 979c96b74cad..d5ed64543bbf 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -81,7 +81,7 @@ static void binder_insert_free_buffer(struct binder_alloc *alloc,
 	new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
 
 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-		     "%d: add free buffer, size %zd, at %pK\n",
+		     "%d: add free buffer, size %zd, at %p\n",
 		      alloc->pid, new_buffer_size, new_buffer);
 
 	while (*p) {
@@ -572,7 +572,7 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 	}
 
 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-		     "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
+		     "%d: binder_alloc_buf size %zd got buffer %p size %zd\n",
 		      alloc->pid, size, buffer, buffer_size);
 
 	/*
@@ -748,7 +748,7 @@ static void binder_free_buf_locked(struct binder_alloc *alloc,
 		ALIGN(buffer->extra_buffers_size, sizeof(void *));
 
 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-		     "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
+		     "%d: binder_free_buf %p size %zd buffer_size %zd\n",
 		      alloc->pid, buffer, size, buffer_size);
 
 	BUG_ON(buffer->free);

---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20260107-restricted-pointers-binder-8ed32869f6d8

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@...utronix.de>