linux-kernel - [PATCH] bus: fsl-mc: fix invalid free in fsl_mc_device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200708184524.1809-1-trix@redhat.com>
Date:   Wed,  8 Jul 2020 11:45:24 -0700
From:   trix@...hat.com
To:     stuyoder@...il.com, laurentiu.tudor@....com,
        gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, Tom Rix <trix@...hat.com>
Subject: [PATCH] bus: fsl-mc: fix invalid free in fsl_mc_device_add

From: Tom Rix <trix@...hat.com>

clang static analysis flags this error

fsl-mc-bus.c:695:2: warning: Attempt to free released memory [unix.Malloc]
        kfree(mc_dev);
        ^~~~~~~~~~~~~

The problem block of code is

		mc_bus = kzalloc(sizeof(*mc_bus), GFP_KERNEL);
		if (!mc_bus)
			return -ENOMEM;

		mc_dev = &mc_bus->mc_dev;

mc_bus's structure contains a mc_dev element,
freeing it later is not appropriate.

So check if mc_bus was allocated before freeing mc_dev

This is a case where checkpatch

WARNING: kfree(NULL) is safe and this check is probably not required
+	if (mc_bus)
+		kfree(mc_bus);

is wrong.

Fixes: a042fbed0290 ("staging: fsl-mc: simplify couple of deallocations")

Signed-off-by: Tom Rix <trix@...hat.com>
---
 drivers/bus/fsl-mc/fsl-mc-bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index 40526da5c6a6..7390e56661a0 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -691,8 +691,10 @@ int fsl_mc_device_add(struct fsl_mc_obj_desc *obj_desc,
 
 error_cleanup_dev:
 	kfree(mc_dev->regions);
-	kfree(mc_bus);
-	kfree(mc_dev);
+	if (mc_bus)
+		kfree(mc_bus);
+	else
+		kfree(mc_dev);
 
 	return error;
 }
-- 
2.18.1