netdev - [PATCH] mISDN: Fix memory leak in dsp_hwec

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Message-Id: <20250828081457.36061-1-linmq006@gmail.com>
Date: Thu, 28 Aug 2025 16:14:57 +0800
From: Miaoqian Lin <linmq006@...il.com>
To: Karsten Keil <isdn@...ux-pingi.de>,
	Laura Abbott <labbott@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: linmq006@...il.com
Subject: [PATCH] mISDN: Fix memory leak in dsp_hwec_enable()

dsp_hwec_enable() allocates dup pointer by kstrdup(arg),
but then it updates dup variable by strsep(&dup, ",").
As a result when it calls kfree(dup), the dup variable may be
a modified pointer that no longer points to the original allocated
memory, causing a memory leak.

The issue is the same pattern as fixed in commit c6a502c22999
("mISDN: Fix memory leak in dsp_pipeline_build()").

Fixes: 9a4381618262 ("mISDN: Remove VLAs")
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
 drivers/isdn/mISDN/dsp_hwec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/isdn/mISDN/dsp_hwec.c b/drivers/isdn/mISDN/dsp_hwec.c
index 0b3f29195330..0cd216e28f00 100644
--- a/drivers/isdn/mISDN/dsp_hwec.c
+++ b/drivers/isdn/mISDN/dsp_hwec.c
@@ -51,14 +51,14 @@ void dsp_hwec_enable(struct dsp *dsp, const char *arg)
 		goto _do;
 
 	{
-		char *dup, *tok, *name, *val;
+		char *dup, *next, *tok, *name, *val;
 		int tmp;
 
-		dup = kstrdup(arg, GFP_ATOMIC);
+		dup = next = kstrdup(arg, GFP_ATOMIC);
 		if (!dup)
 			return;
 
-		while ((tok = strsep(&dup, ","))) {
+		while ((tok = strsep(&next, ","))) {
 			if (!strlen(tok))
 				continue;
 			name = strsep(&tok, "=");
-- 
2.39.5 (Apple Git-154)