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Date:   Thu,  2 Nov 2023 18:59:05 +0000
In-Reply-To: <20231102185934.773885-1-cmllamas@google.com>
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Message-ID: <20231102185934.773885-5-cmllamas@google.com>
Subject: [PATCH 04/21] binder: fix async space check for 0-sized buffers
From:   Carlos Llamas <cmllamas@google.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "=?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?=" <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <brauner@kernel.org>,
        Carlos Llamas <cmllamas@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Sherry Yang <sherryy@android.com>
Cc:     linux-kernel@vger.kernel.org, kernel-team@android.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Move the padding of 0-sized buffers to an earlier stage to account for
this round up during the alloc->free_async_space check.

Fixes: 74310e06be4d ("android: binder: Move buffer out of area shared with user space")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---
 drivers/android/binder_alloc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 046c3ae9eb8f..9b28d0f9666d 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -407,6 +407,10 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 				alloc->pid, extra_buffers_size);
 		return ERR_PTR(-EINVAL);
 	}
+
+	/* Pad 0-size buffers so they get assigned unique addresses */
+	size = max(size, sizeof(void *));
+
 	if (is_async &&
 	    alloc->free_async_space < size + sizeof(struct binder_buffer)) {
 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
@@ -415,9 +419,6 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 		return ERR_PTR(-ENOSPC);
 	}
 
-	/* Pad 0-size buffers so they get assigned unique addresses */
-	size = max(size, sizeof(void *));
-
 	while (n) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
 		BUG_ON(!buffer->free);
-- 
2.42.0.869.gea05f2083d-goog