[120/190] Revert "tty: atmel_serial: fix a potential NULL pointer dereference"
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Message ID 20210421130105.1226686-121-gregkh@linuxfoundation.org
State New, archived
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Series
  • Revertion of all of the umn.edu commits
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Commit Message

Greg KH April 21, 2021, 12:59 p.m. UTC
This reverts commit c85be041065c0be8bc48eda4c45e0319caf1d0e5.

Commits from @umn.edu addresses have been found to be submitted in "bad
faith" to try to test the kernel community's ability to review "known
malicious" changes.  The result of these submissions can be found in a
paper published at the 42nd IEEE Symposium on Security and Privacy
entitled, "Open Source Insecurity: Stealthily Introducing
Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
of Minnesota) and Kangjie Lu (University of Minnesota).

Because of this, all submissions from this group must be reverted from
the kernel tree and will need to be re-reviewed again to determine if
they actually are a valid fix.  Until that work is complete, remove this
change to ensure that no problems are being introduced into the
codebase.

Cc: Kangjie Lu <kjlu@umn.edu>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: stable <stable@vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/atmel_serial.c | 4 ----
 1 file changed, 4 deletions(-)

Comments

Jiri Slaby April 22, 2021, 5:18 a.m. UTC | #1
On 21. 04. 21, 14:59, Greg Kroah-Hartman wrote:
> This reverts commit c85be041065c0be8bc48eda4c45e0319caf1d0e5.
> 
> Commits from @umn.edu addresses have been found to be submitted in "bad
> faith" to try to test the kernel community's ability to review "known
> malicious" changes.  The result of these submissions can be found in a
> paper published at the 42nd IEEE Symposium on Security and Privacy
> entitled, "Open Source Insecurity: Stealthily Introducing
> Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
> of Minnesota) and Kangjie Lu (University of Minnesota).
> 
> Because of this, all submissions from this group must be reverted from
> the kernel tree and will need to be re-reviewed again to determine if
> they actually are a valid fix.  Until that work is complete, remove this
> change to ensure that no problems are being introduced into the
> codebase.
> 
> Cc: Kangjie Lu <kjlu@umn.edu>
> Cc: Richard Genoud <richard.genoud@gmail.com>
> Cc: stable <stable@vger.kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>   drivers/tty/serial/atmel_serial.c | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index a24e5c2b30bc..9786d8e5f04f 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -1256,10 +1256,6 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
>   					 sg_dma_len(&atmel_port->sg_rx)/2,
>   					 DMA_DEV_TO_MEM,
>   					 DMA_PREP_INTERRUPT);
> -	if (!desc) {
> -		dev_err(port->dev, "Preparing DMA cyclic failed\n");
> -		goto chan_err;
> -	}

I cannot find anything malicious in the original fix:
* port->dev is valid for dev_err
* dmaengine_prep_dma_cyclic returns NULL in case of error
* chan_err invokes atmel_release_rx_dma which undoes the previous 
initialization code.

Hence a NACK from me for the revert.

>   	desc->callback = atmel_complete_rx_dma;
>   	desc->callback_param = port;
>   	atmel_port->desc_rx = desc;
>
Richard Genoud April 22, 2021, 6:47 a.m. UTC | #2
Le 22/04/2021 à 07:18, Jiri Slaby a écrit :
> On 21. 04. 21, 14:59, Greg Kroah-Hartman wrote:
>> This reverts commit c85be041065c0be8bc48eda4c45e0319caf1d0e5.
>>
>> Commits from @umn.edu addresses have been found to be submitted in "bad
>> faith" to try to test the kernel community's ability to review "known
>> malicious" changes.  The result of these submissions can be found in a
>> paper published at the 42nd IEEE Symposium on Security and Privacy
>> entitled, "Open Source Insecurity: Stealthily Introducing
>> Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
>> of Minnesota) and Kangjie Lu (University of Minnesota).
>>
>> Because of this, all submissions from this group must be reverted from
>> the kernel tree and will need to be re-reviewed again to determine if
>> they actually are a valid fix.  Until that work is complete, remove this
>> change to ensure that no problems are being introduced into the
>> codebase.
>>
>> Cc: Kangjie Lu <kjlu@umn.edu>
>> Cc: Richard Genoud <richard.genoud@gmail.com>
>> Cc: stable <stable@vger.kernel.org>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> ---
>>   drivers/tty/serial/atmel_serial.c | 4 ----
>>   1 file changed, 4 deletions(-)
>>
>> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
>> index a24e5c2b30bc..9786d8e5f04f 100644
>> --- a/drivers/tty/serial/atmel_serial.c
>> +++ b/drivers/tty/serial/atmel_serial.c
>> @@ -1256,10 +1256,6 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
>>                        sg_dma_len(&atmel_port->sg_rx)/2,
>>                        DMA_DEV_TO_MEM,
>>                        DMA_PREP_INTERRUPT);
>> -    if (!desc) {
>> -        dev_err(port->dev, "Preparing DMA cyclic failed\n");
>> -        goto chan_err;
>> -    }
> 
> I cannot find anything malicious in the original fix:
> * port->dev is valid for dev_err
> * dmaengine_prep_dma_cyclic returns NULL in case of error
> * chan_err invokes atmel_release_rx_dma which undoes the previous initialization code.
> 
> Hence a NACK from me for the revert.

I agree with your NACK.
Back at the time (march 2019), I reviewed the changed and asked for a 2nd version and
I didn't found anything suspicious.
But the more eyes, the better.

cf http://lkml.iu.edu/hypermail/linux/kernel/1903.1/05858.html

> 
>>       desc->callback = atmel_complete_rx_dma;
>>       desc->callback_param = port;
>>       atmel_port->desc_rx = desc;
>>
> 
>
Greg KH April 26, 2021, 5:04 p.m. UTC | #3
On Thu, Apr 22, 2021 at 06:47:20AM +0000, Richard Genoud wrote:
> 
> 
> Le 22/04/2021 à 07:18, Jiri Slaby a écrit :
> > On 21. 04. 21, 14:59, Greg Kroah-Hartman wrote:
> > > This reverts commit c85be041065c0be8bc48eda4c45e0319caf1d0e5.
> > > 
> > > Commits from @umn.edu addresses have been found to be submitted in "bad
> > > faith" to try to test the kernel community's ability to review "known
> > > malicious" changes.  The result of these submissions can be found in a
> > > paper published at the 42nd IEEE Symposium on Security and Privacy
> > > entitled, "Open Source Insecurity: Stealthily Introducing
> > > Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
> > > of Minnesota) and Kangjie Lu (University of Minnesota).
> > > 
> > > Because of this, all submissions from this group must be reverted from
> > > the kernel tree and will need to be re-reviewed again to determine if
> > > they actually are a valid fix.  Until that work is complete, remove this
> > > change to ensure that no problems are being introduced into the
> > > codebase.
> > > 
> > > Cc: Kangjie Lu <kjlu@umn.edu>
> > > Cc: Richard Genoud <richard.genoud@gmail.com>
> > > Cc: stable <stable@vger.kernel.org>
> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > ---
> > >   drivers/tty/serial/atmel_serial.c | 4 ----
> > >   1 file changed, 4 deletions(-)
> > > 
> > > diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> > > index a24e5c2b30bc..9786d8e5f04f 100644
> > > --- a/drivers/tty/serial/atmel_serial.c
> > > +++ b/drivers/tty/serial/atmel_serial.c
> > > @@ -1256,10 +1256,6 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
> > >                        sg_dma_len(&atmel_port->sg_rx)/2,
> > >                        DMA_DEV_TO_MEM,
> > >                        DMA_PREP_INTERRUPT);
> > > -    if (!desc) {
> > > -        dev_err(port->dev, "Preparing DMA cyclic failed\n");
> > > -        goto chan_err;
> > > -    }
> > 
> > I cannot find anything malicious in the original fix:
> > * port->dev is valid for dev_err
> > * dmaengine_prep_dma_cyclic returns NULL in case of error
> > * chan_err invokes atmel_release_rx_dma which undoes the previous initialization code.
> > 
> > Hence a NACK from me for the revert.
> 
> I agree with your NACK.
> Back at the time (march 2019), I reviewed the changed and asked for a 2nd version and
> I didn't found anything suspicious.
> But the more eyes, the better.
> 
> cf http://lkml.iu.edu/hypermail/linux/kernel/1903.1/05858.html

Thanks for the review, now dropped.

greg k-h

Patch
diff mbox series

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index a24e5c2b30bc..9786d8e5f04f 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1256,10 +1256,6 @@  static int atmel_prepare_rx_dma(struct uart_port *port)
 					 sg_dma_len(&atmel_port->sg_rx)/2,
 					 DMA_DEV_TO_MEM,
 					 DMA_PREP_INTERRUPT);
-	if (!desc) {
-		dev_err(port->dev, "Preparing DMA cyclic failed\n");
-		goto chan_err;
-	}
 	desc->callback = atmel_complete_rx_dma;
 	desc->callback_param = port;
 	atmel_port->desc_rx = desc;