linux-kernel - [PATCH] sysctl: Reduce dput(child) calls in proc_sys_fill

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Message-ID: <7be4c6d7-4da1-43bb-b081-522a8339fd99@web.de>
Date: Thu, 26 Sep 2024 10:20:34 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: linux-fsdevel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
 Joel Granados <j.granados@...sung.com>, Kees Cook <kees@...nel.org>,
 Luis Chamberlain <mcgrof@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org
Subject: [PATCH] sysctl: Reduce dput(child) calls in proc_sys_fill_cache()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Thu, 26 Sep 2024 10:10:33 +0200

A dput(child) call was immediately used after an error pointer check
for a d_splice_alias() call in this function implementation.
Thus call such a function instead directly before the check.

This issue was transformed by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 fs/proc/proc_sysctl.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index d11ebc055ce0..97547de58218 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -698,11 +698,11 @@ static bool proc_sys_fill_cache(struct file *file,
 			res = d_splice_alias(inode, child);
 			d_lookup_done(child);
 			if (unlikely(res)) {
-				if (IS_ERR(res)) {
-					dput(child);
-					return false;
-				}
 				dput(child);
+
+				if (IS_ERR(res))
+					return false;
+
 				child = res;
 			}
 		}
--
2.46.1