[PATCH v2] fs: ocfs2: Replace strlcpy with sysfs_emit

From: Azeem Shaikh <azeemshaikh38@gmail.com>
To: Mark Fasheh <mark@fasheh.com>, Joel Becker <jlbec@evilplan.org>,
	Joseph Qi <joseph.qi@linux.alibaba.com>,
	Kees Cook <keescook@chromium.org>
Cc: linux-hardening@vger.kernel.org,
	Azeem Shaikh <azeemshaikh38@gmail.com>,
	ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org,
	Christian Brauner <brauner@kernel.org>,
	Dave Chinner <dchinner@redhat.com>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@kernel.org>
Subject: [PATCH v2] fs: ocfs2: Replace strlcpy with sysfs_emit
Date: Thu, 31 Aug 2023 19:38:27 +0000	[thread overview]
Message-ID: <20230831193827.1528867-1-azeemshaikh38@gmail.com> (raw)

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with sysfs_emit().

Direct replacement is safe here since its ok for `kernel_param_ops.get()`
to return -errno [3].

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
[3] https://elixir.bootlin.com/linux/v6.5/source/include/linux/moduleparam.h#L52

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
v2:
 * Removes patch [1/2] which replaced module_param_call with module_param_cb.
 * Use sysfs_emit instead of strscpy.

v1:
 * https://lore.kernel.org/all/20230830215426.4181755-1-azeemshaikh38@gmail.com/

 fs/ocfs2/dlmfs/dlmfs.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/ocfs2/dlmfs/dlmfs.c b/fs/ocfs2/dlmfs/dlmfs.c
index 81265123ce6c..b38776ba3306 100644
--- a/fs/ocfs2/dlmfs/dlmfs.c
+++ b/fs/ocfs2/dlmfs/dlmfs.c
@@ -80,8 +80,7 @@ static int param_set_dlmfs_capabilities(const char *val,
 static int param_get_dlmfs_capabilities(char *buffer,
 					const struct kernel_param *kp)
 {
-	return strlcpy(buffer, DLMFS_CAPABILITIES,
-		       strlen(DLMFS_CAPABILITIES) + 1);
+	return sysfs_emit(buffer, DLMFS_CAPABILITIES);
 }
 module_param_call(capabilities, param_set_dlmfs_capabilities,
 		  param_get_dlmfs_capabilities, NULL, 0444);
--
2.42.0.283.g2d96d420d3-goog


