From nobody Sun Feb 8 21:06:50 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E788830F949; Mon, 22 Dec 2025 09:37:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766396265; cv=none; b=Ug0iDxeRLqnqRsjnQFNCvASqiF7pwa8MMKWhDKMlEfV47905LoWJvhY6q8DSi9yyCfXY4FJteZ5k6e6hJdVAebKgza8qYr19FJYCmySTlgTKAuflPvVjZLSVy+/4LtVSZFD5UTBOpsxzm+Pqpreai9yNBASmUhesn/WKYB40ytA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766396265; c=relaxed/simple; bh=VwOk0KrORHi4rzm7L7X2SEpvILp0jvuywJgDjew0cN4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dKear/0SQZESvIb8s4jGF363aqgvcitGq0T1N/owKlt/i84jGEN7wPE8y/ipzNSHBOf8PGMdzP3HdCCQhDGp75qGVc7uYpe/JlA0yCXkxdu9g7yYUWHUwidueklRcHmzkF9WJ4RJTSfHun+FJL7jbkFWgDhWkdmCj1VKH7qg6/c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=buB7uoF3; arc=none smtp.client-ip=220.197.31.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="buB7uoF3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=AN Md3WXbGHnt1eZja1yDTXINJmeObLlJnACM7kb9+Kw=; b=buB7uoF34Boj5aM20H gLTNOXDJm6KmuNKDCB9kCzPeSehledCFaMlBwIorUo0WdaP0N1EDWe6LZsmO28bP zyznh+Nr1sf6W36STHinaGpZPPwWaFdLof/veQN0oIhKm1E568iIgfR6YH8QGuaP g12EiFR8EaGgIiTYcuGMIDN8I= Received: from mi-work.mioffice.cn (unknown []) by gzsmtp4 (Coremail) with SMTP id PygvCgB3y6s5EUlpL+Z3IQ--.37483S4; Mon, 22 Dec 2025 17:37:01 +0800 (CST) From: yangshiguang1011@163.com To: gregkh@linuxfoundation.org Cc: rafael@kernel.org, dakr@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, yangshiguang@xiaomi.com, stable@vger.kernel.org Subject: [PATCH] debugfs: Fix NULL pointer dereference at debugfs_read_file_str Date: Mon, 22 Dec 2025 17:36:16 +0800 Message-ID: <20251222093615.663252-2-yangshiguang1011@163.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: PygvCgB3y6s5EUlpL+Z3IQ--.37483S4 X-Coremail-Antispam: 1Uf129KBjvdXoWrZF4xXw18ury5ur1DCFykZrb_yoWDCrbEq3 48Xayktw45JrW7Xr4xC345ZrWv9a1rCr4furZxtrZxtrW7J397Gw1kuwn3Xr93G3y8Gr1r Jry5Jr9xGF1IyjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IU1WSrUUUUUU== X-CM-SenderInfo: 51dqw25klj3ttqjriiqr6rljoofrz/xtbC3h0A5WlJET1fIAAA3V Content-Type: text/plain; charset="utf-8" From: yangshiguang 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. 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 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; =20 str =3D *(char **)file->private_data; + if (!str) + return -EINVAL; + len =3D strlen(str) + 1; copy =3D kmalloc(len, GFP_KERNEL); if (!copy) { --=20 2.43.0