linux-kernel - [PATCH v2 2/2] binder: Validate the default binderfs device names.

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Message-Id: <20190806184007.60739-3-hridya@google.com>
Date:   Tue,  6 Aug 2019 11:40:06 -0700
From:   Hridya Valsaraju <hridya@...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 <christian@...uner.io>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com, Hridya Valsaraju <hridya@...gle.com>,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH v2 2/2] binder: Validate the default binderfs device names.

Length of a binderfs device name cannot exceed BINDERFS_MAX_NAME.
This patch adds a check in binderfs_init() to ensure the same
for the default binder devices that will be created in every
binderfs instance.

Co-developed-by: Christian Brauner <christian.brauner@...ntu.com>
Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
Signed-off-by: Hridya Valsaraju <hridya@...gle.com>
---
 drivers/android/binderfs.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index 886b4e0f482f..52c8bd361906 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -572,6 +572,18 @@ static struct file_system_type binder_fs_type = {
 int __init init_binderfs(void)
 {
 	int ret;
+	const char *name;
+	size_t len;
+
+	/* Verify that the default binderfs device names are valid. */
+	name = binder_devices_param;
+	for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
+		if (len > BINDERFS_MAX_NAME)
+			return -E2BIG;
+		name += len;
+		if (*name == ',')
+			name++;
+	}
 
 	/* Allocate new major number for binderfs. */
 	ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
-- 
2.22.0.770.g0f2c4a37fd-goog