linux-kernel - Re: [PATCH] mtd: fix memory leak

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

Message-Id: <168EA60D-68D1-4281-A0C2-22B2B598AFE1@googlemail.com>
Date:	Sun, 30 Jan 2011 18:35:48 +0100
From:	Mathias Krause <minipli@...glemail.com>
To:	dedekind1@...il.com
Cc:	linux-mtd@...ts.infradead.org,
	David Woodhouse <dwmw2@...radead.org>,
	Joern Engel <joern@...ybastard.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: fix memory leak

On 30.01.2011 at 15:52, Artem Bityutskiy wrote:
> Hi,
> 
> On Sun, 2011-01-30 at 10:31 +0100, Mathias Krause wrote:
>> diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
>> index 5239328..8d28fa0 100644
>> --- a/drivers/mtd/devices/phram.c
>> +++ b/drivers/mtd/devices/phram.c
>> @@ -117,6 +117,7 @@ static void unregister_devices(void)
>> 	list_for_each_entry_safe(this, safe, &phram_list, list) {
>> 		del_mtd_device(&this->mtd);
>> 		iounmap(this->mtd.priv);
>> +		kfree(this->mtd.name);
>> 		kfree(this);
>> 	}
> 
> Since register_device() did not allocate it, unregister_devices() should
> not free it.

I agree with you, the internal API is a little quirky regarding that point. register_device() should strdup() the name and not just blindly use it. But since the memory for name was already allocated via kmalloc() in phram_setup() it seems a little nitpicky to copy it once again in register_device().

> Hence, I think it is better to free(name) just after
> calling unregister_devices().

This is not possible because unregister_devices() unregisters all devices, not just a single instance. Though name must be freed for every object in the list. After unregister_devices() returns the list is empty and no pointer to the memory locations do exist any more. So my patch was the straight forward fix for the memory leak.

Regards,
Mathias--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/