linux-kernel - [PATCH] fs/9p: Improve exception handling in v9fs_session

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Date: Thu, 28 Dec 2023 21:01:49 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: v9fs@...ts.linux.dev, kernel-janitors@...r.kernel.org,
 Christian Schönebeck <linux_oss@...debyte.com>,
 Dominique Martinet <asmadeus@...ewreck.org>,
 Eric Van Hensbergen <ericvh@...nel.org>, Latchesar Ionkov <lucho@...kov.net>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] fs/9p: Improve exception handling in v9fs_session_init()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Thu, 28 Dec 2023 20:47:18 +0100

The kfree() function was called in up to two cases by
the v9fs_session_init() function during error handling
even if the passed variable contained a null pointer.
This issue was detected by using the Coccinelle software.

* Thus return directly after a call of the function “kstrdup” failed
  at the beginning.

* Adjust jump targets.

* Delete an initialisation (for the variable “rc”)
  which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 fs/9p/v9fs.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 61dbe52bb3a3..874a36303b72 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -392,15 +392,18 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 		  const char *dev_name, char *data)
 {
 	struct p9_fid *fid;
-	int rc = -ENOMEM;
+	int rc;

 	v9ses->uname = kstrdup(V9FS_DEFUSER, GFP_KERNEL);
 	if (!v9ses->uname)
-		goto err_names;
+		return ERR_PTR(-ENOMEM);

 	v9ses->aname = kstrdup(V9FS_DEFANAME, GFP_KERNEL);
-	if (!v9ses->aname)
-		goto err_names;
+	if (!v9ses->aname) {
+		rc = -ENOMEM;
+		goto free_uname;
+	}
+
 	init_rwsem(&v9ses->rename_sem);

 	v9ses->uid = INVALID_UID;
@@ -489,8 +492,9 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 #endif
 	p9_client_destroy(v9ses->clnt);
 err_names:
-	kfree(v9ses->uname);
 	kfree(v9ses->aname);
+free_uname:
+	kfree(v9ses->uname);
 	return ERR_PTR(rc);
 }

--
2.43.0