linux-kernel - [PATCH] stm class: fix a double free in stm_register

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Date:   Wed, 20 Nov 2019 23:26:32 +0800
From:   Wen Yang <wenyang@...ux.alibaba.com>
To:     alexander.shishkin@...ux.intel.com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...co
Cc:     zhiche.yy@...baba-inc.com, xlpang@...ux.alibaba.com,
        Wen Yang <wenyang@...ux.alibaba.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] stm class: fix a double free in stm_register_device()

In the error path of stm_register_device(), the kfree is
unnecessary, as the put_device() before it ends up calling
stm_device_release() to free stm_device.

Fixes: 7bd1d4093c2fa ("stm class: Introduce an abstraction for System Trace Module devices")
Signed-off-by: Wen Yang <wenyang@...ux.alibaba.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...com>
Cc: linux-stm32@...md-mailman.stormreply.com
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
---
 drivers/hwtracing/stm/core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 2712e69..55c69d8 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -868,8 +868,10 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
 		return -ENOMEM;
 
 	stm->major = register_chrdev(0, stm_data->name, &stm_fops);
-	if (stm->major < 0)
-		goto err_free;
+	if (stm->major < 0) {
+		vfree(stm);
+		return err;
+	}
 
 	device_initialize(&stm->dev);
 	stm->dev.devt = MKDEV(stm->major, 0);
@@ -915,8 +917,6 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
 
 	/* matches device_initialize() above */
 	put_device(&stm->dev);
-err_free:
-	vfree(stm);
 
 	return err;
 }
-- 
1.8.3.1