From: Jon Hunter <jonathanh@nvidia.com>
To: Kees Cook <keescook@chromium.org>,
Gen Zhang <blackgod016574@gmail.com>,
Greg KH <gregkh@linuxfoundation.org>
Cc: <jslaby@suse.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] consolemap: Fix a memory leaking bug in drivers/tty/vt/consolemap.c
Date: Fri, 24 May 2019 10:37:59 +0100 [thread overview]
Message-ID: <b99d0da6-a1d6-1c04-66ff-b2937d21d346@nvidia.com> (raw)
In-Reply-To: <201905230952.B47ADA17A@keescook>
Kees,
On 23/05/2019 17:54, Kees Cook wrote:
> On Thu, May 23, 2019 at 08:34:52AM +0800, Gen Zhang wrote:
>> In function con_insert_unipair(), when allocation for p2 and p1[n]
>> fails, ENOMEM is returned, but previously allocated p1 is not freed,
>> remains as leaking memory. Thus we should free p1 as well when this
>> allocation fails.
>>
>> Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
>
> As far as I can see this is correct, as it's just restoring the prior
> state before the p1 allocation.
Are you sure this is correct? It looks like p1 is only allocated if
p->uni_pgdir[n = unicode >> 11] == NULL.
I only mention this because I have seen a few patches from Gen today
regarding memory leaks and devm_kzalloc() that are not correct.
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
>> ---
>> diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
>> index b28aa0d..79fcc96 100644
>> --- a/drivers/tty/vt/consolemap.c
>> +++ b/drivers/tty/vt/consolemap.c
>> @@ -489,7 +489,11 @@ con_insert_unipair(struct uni_pagedir *p, u_short unicode, u_short fontpos)
>> p2 = p1[n = (unicode >> 6) & 0x1f];
>> if (!p2) {
>> p2 = p1[n] = kmalloc_array(64, sizeof(u16), GFP_KERNEL);
>> - if (!p2) return -ENOMEM;
>> + if (!p2) {
>> + kfree(p1);
>> + p->uni_pgdir[n] = NULL;
>> + return -ENOMEM;
>> + }
>> memset(p2, 0xff, 64*sizeof(u16)); /* No glyphs for the characters (yet) */
>> }
>>
>> ---
Cheers
Jon
--
nvpublic
next prev parent reply other threads:[~2019-05-24 9:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 9:29 [PATCH] consolemap: Fix a memory leaking bug in drivers/tty/vt/consolemap.c Gen Zhang
2019-05-21 20:44 ` Kees Cook
2019-05-22 1:50 ` Gen Zhang
2019-05-22 20:54 ` Kees Cook
2019-05-23 0:29 ` Gen Zhang
2019-05-23 0:34 ` [PATCH v2] " Gen Zhang
2019-05-23 16:54 ` Kees Cook
2019-05-24 2:14 ` Gen Zhang
2019-05-24 2:19 ` [PATCH v2] consolemap: Fix a memory leaking bug in con_insert_unipair() Gen Zhang
2019-05-24 8:02 ` Greg KH
2019-05-24 9:37 ` Jon Hunter [this message]
2019-05-25 6:04 ` [PATCH v2] consolemap: Fix a memory leaking bug in drivers/tty/vt/consolemap.c Kees Cook
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