On Mon, Dec 22, 2025 at 05:36:16PM +0800, yangshiguang1011@163.com wrote:
From: yangshiguang yangshiguang@xiaomi.com
Check in debugfs_read_file_str() if the string pointer is NULL.
When creating a node using debugfs_create_str(), the string parameter value can be NULL to indicate empty/unused/ignored.
Why would you create an empty debugfs string file? That is not ok, we should change that to not allow this.
However, reading this node using debugfs_read_file_str() will cause a kernel panic. This should not be fatal, so return an invalid error.
Signed-off-by: yangshiguang yangshiguang@xiaomi.com Fixes: 9af0440ec86e ("debugfs: Implement debugfs_create_str()") Cc: stable@vger.kernel.org
fs/debugfs/file.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 3ec3324c2060..a22ff0ceb230 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -1026,6 +1026,9 @@ ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf, return ret; str = *(char **)file->private_data;
- if (!str)
return -EINVAL;
What in kernel user causes this to happen? Let's fix that up instead please.
thanks,
greg k-h