[PATCH] Check whether divisor is non-zero before division

[PATCH] Check whether divisor is non-zero before division

[Shichao Lai]

Since uzonesize may be zero, so a judgement for non-zero is nessesary.

Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yue sun <samsun1006219@gmail.com>
Signed-off-by: Shichao Lai <shichaorai@gmail.com>
---
 drivers/usb/storage/alauda.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
index 115f05a6201a..db075a8c03cb 100644
--- a/drivers/usb/storage/alauda.c
+++ b/drivers/usb/storage/alauda.c
@@ -947,6 +947,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
 	sg = NULL;
 
 	while (sectors > 0) {
+		if (!uzonesize)
+			return USB_STOR_TRANSPORT_ERROR;
 		unsigned int zone = lba / uzonesize; /* integer division */
 		unsigned int lba_offset = lba - (zone * uzonesize);
 		unsigned int pages;
-- 
2.34.1

Re: [PATCH] Check whether divisor is non-zero before division

[Greg KH]

On Thu, May 23, 2024 at 03:22:42PM +0800, Shichao Lai wrote:
> Since uzonesize may be zero, so a judgement for non-zero is nessesary.
> 
> Reported-by: xingwei lee <xrivendell7@gmail.com>
> Reported-by: yue sun <samsun1006219@gmail.com>
> Signed-off-by: Shichao Lai <shichaorai@gmail.com>
> ---
>  drivers/usb/storage/alauda.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
> index 115f05a6201a..db075a8c03cb 100644
> --- a/drivers/usb/storage/alauda.c
> +++ b/drivers/usb/storage/alauda.c
> @@ -947,6 +947,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
>  	sg = NULL;
>  
>  	while (sectors > 0) {
> +		if (!uzonesize)
> +			return USB_STOR_TRANSPORT_ERROR;
>  		unsigned int zone = lba / uzonesize; /* integer division */
>  		unsigned int lba_offset = lba - (zone * uzonesize);
>  		unsigned int pages;
> -- 
> 2.34.1
> 
> 

Looks good, thanks!  I'll queue this up after 6.10-rc1 is out.

greg k-h

Re: [PATCH] Check whether divisor is non-zero before division

[Oliver Neukum]

On 23.05.24 09:22, Shichao Lai wrote:

Hi,

> Since uzonesize may be zero, so a judgement for non-zero is nessesary.
> 
> Reported-by: xingwei lee <xrivendell7@gmail.com>
> Reported-by: yue sun <samsun1006219@gmail.com>
> Signed-off-by: Shichao Lai <shichaorai@gmail.com>
> ---
>   drivers/usb/storage/alauda.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
> index 115f05a6201a..db075a8c03cb 100644
> --- a/drivers/usb/storage/alauda.c
> +++ b/drivers/usb/storage/alauda.c
> @@ -947,6 +947,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
>   	sg = NULL;
>   
>   	while (sectors > 0) {
> +		if (!uzonesize)
> +			return USB_STOR_TRANSPORT_ERROR;

May I point out that uzonesize does not change in this function?
There is no need to retest within the loop.

>   		unsigned int zone = lba / uzonesize; /* integer division */
>   		unsigned int lba_offset = lba - (zone * uzonesize);
>   		unsigned int pages;

Secondly, alauda_write_lba() has the same issue.
You also need to check in alauda_write_data().

	Regards
		Oliver

Re: [PATCH] Check whether divisor is non-zero before division

[shichao lai]

On Thu, May 23, 2024 at 4:18 PM Oliver Neukum <oneukum@suse.com> wrote:
>
> On 23.05.24 09:22, Shichao Lai wrote:
>
> Hi,
>
> > Since uzonesize may be zero, so a judgement for non-zero is nessesary.
> >
> > Reported-by: xingwei lee <xrivendell7@gmail.com>
> > Reported-by: yue sun <samsun1006219@gmail.com>
> > Signed-off-by: Shichao Lai <shichaorai@gmail.com>
> > ---
> >   drivers/usb/storage/alauda.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
> > index 115f05a6201a..db075a8c03cb 100644
> > --- a/drivers/usb/storage/alauda.c
> > +++ b/drivers/usb/storage/alauda.c
> > @@ -947,6 +947,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
> >       sg = NULL;
> >
> >       while (sectors > 0) {
> > +             if (!uzonesize)
> > +                     return USB_STOR_TRANSPORT_ERROR;
>
> May I point out that uzonesize does not change in this function?
> There is no need to retest within the loop.
>
> >               unsigned int zone = lba / uzonesize; /* integer division */
> >               unsigned int lba_offset = lba - (zone * uzonesize);
> >               unsigned int pages;
>
> Secondly, alauda_write_lba() has the same issue.
> You also need to check in alauda_write_data().
>
>         Regards
>                 Oliver


Thanks for the helpful tip!
I reviewed the code. Your suggestions can actually avoid repeated checks.
And there is also such a problem in alauda_write_lba().
I am a beginner at making patches. May I commit a patch again which
fixes both issues you mentioned?

Re: [PATCH] Check whether divisor is non-zero before division

[Oliver Neukum]

On 23.05.24 11:12, shichao lai wrote:

> Thanks for the helpful tip!
> I reviewed the code. Your suggestions can actually avoid repeated checks.
> And there is also such a problem in alauda_write_lba().
> I am a beginner at making patches. May I commit a patch again which
> fixes both issues you mentioned?


Hi,

yes, you usually are supposed to change the "[PATCH]" in the
subject line to "[PATCHv2]" and add a line in the log describing
the difference between the first and second version.

	HTH
		Oliver