linux-kernel - Re: [PATCH 4.19 073/168] media: firewire: Using uninitialized values in node

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Date:   Tue, 18 Aug 2020 23:34:53 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 073/168] media: firewire: Using uninitialized values
 in node_probe()

Hi!

> From: Dan Carpenter <dan.carpenter@...cle.com>
> 
> [ Upstream commit 2505a210fc126599013aec2be741df20aaacc490 ]
> 
> If fw_csr_string() returns -ENOENT, then "name" is uninitialized.  So
> then the "strlen(model_names[i]) <= name_len" is true because strlen()
> is unsigned and -ENOENT is type promoted to a very high positive value.
> Then the "strncmp(name, model_names[i], name_len)" uses uninitialized
> data because "name" is uninitialized.

This causes memory leak, AFAICT.

Signed-off-by: Pavel Machek (CIP) <pavel@...x.de>

Best regards,
								Pavel

diff --git a/drivers/media/firewire/firedtv-fw.c b/drivers/media/firewire/firedtv-fw.c
index eaf94b817dbc..2ac9d24d3f0c 100644
--- a/drivers/media/firewire/firedtv-fw.c
+++ b/drivers/media/firewire/firedtv-fw.c
@@ -271,8 +271,10 @@ static int node_probe(struct fw_unit *unit, const struct ieee1394_device_id *id)
 
 	name_len = fw_csr_string(unit->directory, CSR_MODEL,
 				 name, sizeof(name));
-	if (name_len < 0)
-		return name_len;
+	if (name_len < 0) {
+		err = name_len;
+		goto fail_free;
+	}
 	for (i = ARRAY_SIZE(model_names); --i; )
 		if (strlen(model_names[i]) <= name_len &&
 		    strncmp(name, model_names[i], name_len) == 0)



-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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