From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] Net, USB, Option, hso: Do not dereference NULL pointer Date: Sun, 13 Feb 2011 16:56:08 -0800 (PST) Message-ID: <20110213.165608.149817059.davem@davemloft.net> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, netdev@vger.kernel.org, gregkh@suse.de, j.dumon@option.com, f.aben@option.com, d.barow@option.com, ajb@spheresystems.co.uk To: jj@chaosbits.net Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Jesper Juhl Date: Sun, 13 Feb 2011 22:15:35 +0100 (CET) > In drivers/net/usb/hso.c::hso_create_bulk_serial_device() we have this > code: > ... > serial = kzalloc(sizeof(*serial), GFP_KERNEL); > if (!serial) > goto exit; > ... > exit: > hso_free_tiomget(serial); > ... > hso_free_tiomget() directly dereferences its argument, which in the > example above is a NULL pointer, ouch. > I could just add a 'if (serial)' test at the 'exit' label, but since most > freeing functions in the kernel accept NULL pointers (and it seems like > this was also assumed here) I opted to instead change 'hso_free_tiomget()' > so that it is safe to call it with a NULL argument. I also modified the > function to get rid of a pointles conditional before the call to > 'usb_free_urb()' since that function already tests for NULL itself - > besides fixing the NULL deref this change also buys us a few bytes in > size. > Before: > $ size drivers/net/usb/hso.o > text data bss dec hex filename > 32200 592 9960 42752 a700 drivers/net/usb/hso.o > After: > $ size drivers/net/usb/hso.o > text data bss dec hex filename > 32196 592 9960 42748 a6fc drivers/net/usb/hso.o > > Signed-off-by: Jesper Juhl Applied.