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From:   Dongliang Mu <dzm91@hust.edu.cn>
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>,
        Kees Cook <keescook@chromium.org>
Cc:     Dongliang Mu <mudongliangabcd@gmail.com>,
        syzkaller <syzkaller@googlegroups.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] drivers: binderfs: fix memory leak in binderfs_fill_super
Date:   Fri, 12 Aug 2022 21:21:24 +0800
Message-Id: <20220812132124.2053673-1-dzm91@hust.edu.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Dongliang Mu <mudongliangabcd@gmail.com>

In binderfs_fill_super, if s_root is not successfully initialized by
d_make_root, the previous allocated s_sb_info will not be freed since
generic_shutdown_super first checks if sb->s_root and then does
put_super operation. The put_super operation calls binderfs_put_super
to deallocate s_sb_info and put ipc_ns. This will lead to memory leak
in binderfs_fill_super.

Fix this by invoking binderfs_put_super at error sites before s_root
is successfully initialized.

Fixes: 095cf502b31e ("binderfs: port to new mount api")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
---
 drivers/android/binderfs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index 588d753a7a19..20f5bc77495f 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -710,8 +710,10 @@ static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	info->mount_opts.stats_mode = ctx->stats_mode;
 
 	inode = new_inode(sb);
-	if (!inode)
+	if (!inode) {
+		binderfs_put_super(sb);
 		return -ENOMEM;
+	}
 
 	inode->i_ino = FIRST_INODE;
 	inode->i_fop = &simple_dir_operations;
@@ -721,8 +723,10 @@ static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	set_nlink(inode, 2);
 
 	sb->s_root = d_make_root(inode);
-	if (!sb->s_root)
+	if (!sb->s_root) {
+		binderfs_put_super(sb);
 		return -ENOMEM;
+	}
 
 	ret = binderfs_binder_ctl_create(sb);
 	if (ret)
-- 
2.25.1