linux-kernel - Re: [PATCH] usbip: Fix free of unallocated memory in vhci tx

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: <936d4cf8-cd5a-a297-8298-e9bc5d3c193d@kernel.org>
Date:   Mon, 21 Oct 2019 13:28:54 -0600
From:   shuah <shuah@...nel.org>
To:     Julia Lawall <julia.lawall@...6.fr>,
        Suwan Kim <suwan.kim027@...il.com>
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, valentina.manea.m@...il.com,
        kbuild test robot <lkp@...el.com>, shuah <shuah@...nel.org>
Subject: Re: [PATCH] usbip: Fix free of unallocated memory in vhci tx

On 10/21/19 9:08 AM, Julia Lawall wrote:
> 
> 
> On Mon, 21 Oct 2019, Suwan Kim wrote:
> 
>> iso_buffer should be set to NULL after use and free in the while loop.
>> In the case of isochronous URB in the while loop, iso_buffer is
>> allocated and after sending it to server, buffer is deallocated. And
>> then, if the next URB in the while loop is not a isochronous pipe,
>> iso_buffer still holds the previously deallocated buffer address and
>> kfree tries to free wrong buffer address.
>>
>> Fixes: ea44d190764b (“usbip: Implement SG support to vhci-hcd and stub driver”)
>> Reported-by: kbuild test robot <lkp@...el.com>
>> Reported-by: Julia Lawall <julia.lawall@...6.fr>
>> Signed-off-by: Suwan Kim <suwan.kim027@...il.com>
>> ---
>>   drivers/usb/usbip/vhci_tx.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
>> index c3803785f6ef..b290e810d11b 100644
>> --- a/drivers/usb/usbip/vhci_tx.c
>> +++ b/drivers/usb/usbip/vhci_tx.c
>> @@ -73,6 +73,7 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
>>   		memset(&pdu_header, 0, sizeof(pdu_header));
>>   		memset(&msg, 0, sizeof(msg));
>>   		memset(&iov, 0, sizeof(iov));
>> +		iso_buffer = NULL;
> 
> Somehow I would have put it after the kfree, since the kfree makes the
> value invalid.  iso_buffer is already initialized to NULL for the first
> iteration.  If you want to put the setting to NULL at the top of the loop,
> maybe the = NULL in the first line should be removed.
> 

It makes sense to clear it after kfree() on line 150.

This kfree() and clearing iso_buffer are necessary only for
PIPE_ISOCHRONOUS case.

Please add a comment above that this is for isoc case.

thanks,
-- Shuah