[PATCH 2/2] ocfs2: Replace strlcpy with strscpy

From: Azeem Shaikh <azeemshaikh38@gmail.com>
To: Mark Fasheh <mark@fasheh.com>, Joel Becker <jlbec@evilplan.org>,
	Joseph Qi <joseph.qi@linux.alibaba.com>
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>,
	Jeff Layton <jlayton@kernel.org>
Subject: [PATCH 2/2] ocfs2: Replace strlcpy with strscpy
Date: Wed, 30 Aug 2023 21:54:26 +0000	[thread overview]
Message-ID: <20230830215426.4181755-3-azeemshaikh38@gmail.com> (raw)
In-Reply-To: <20230830215426.4181755-1-azeemshaikh38@gmail.com>

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 strscpy().

Direct replacement is assumed to be safe here since
it's ok for `kernel_param_ops.get()` to return -errno [3].
This changes the behavior such that instead of silently ignoring the
case when sizeof(@buffer) < DLMFS_CAPABILITIES, we now return error.

[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>
---
 fs/ocfs2/dlmfs/dlmfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ocfs2/dlmfs/dlmfs.c b/fs/ocfs2/dlmfs/dlmfs.c
index 33e529de93b2..b001eccdd2f3 100644
--- a/fs/ocfs2/dlmfs/dlmfs.c
+++ b/fs/ocfs2/dlmfs/dlmfs.c
@@ -80,7 +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,
+	return strscpy(buffer, DLMFS_CAPABILITIES,
 		       strlen(DLMFS_CAPABILITIES) + 1);
 }
 static const struct kernel_param_ops dlmfs_capabilities_ops = {
--
2.42.0.283.g2d96d420d3-goog

