[PATCH v2] usb-storage: Check whether divisor is non-zero before division

[PATCH v2] usb-storage: Check whether divisor is non-zero before division

[Shichao Lai]

Since uzonesize may be zero, so judgements for non-zero
are nessesary in both place.

Changes since v1:
- Add one more check in alauda_write_lba().
- Move check ahead of loop in alauda_read_data().

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 | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
index 115f05a6201a..17c73acd3b02 100644
--- a/drivers/usb/storage/alauda.c
+++ b/drivers/usb/storage/alauda.c
@@ -813,6 +813,8 @@ static int alauda_write_lba(struct us_data *us, u16 lba,
 	unsigned char ecc[3];
 	int i, result;
 	unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
+	if (!uzonesize)
+		return USB_STOR_TRANSPORT_ERROR;
 	unsigned int zonesize = MEDIA_INFO(us).zonesize;
 	unsigned int pagesize = MEDIA_INFO(us).pagesize;
 	unsigned int blocksize = MEDIA_INFO(us).blocksize;
@@ -921,6 +923,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
 	unsigned int blocksize = MEDIA_INFO(us).blocksize;
 	unsigned int pagesize = MEDIA_INFO(us).pagesize;
 	unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
+	if (!uzonesize)
+		return USB_STOR_TRANSPORT_ERROR;
 	struct scatterlist *sg;
 	int result;
 
-- 
2.34.1

Re: [PATCH v2] usb-storage: Check whether divisor is non-zero before division

[Greg KH]

On Thu, May 23, 2024 at 07:34:10PM +0800, Shichao Lai wrote:
> Since uzonesize may be zero, so judgements for non-zero
> are nessesary in both place.
> 
> Changes since v1:
> - Add one more check in alauda_write_lba().
> - Move check ahead of loop in alauda_read_data().

Nit, this changes list should go below the --- line, as the
documentation asks for.


> 
> 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 | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
> index 115f05a6201a..17c73acd3b02 100644
> --- a/drivers/usb/storage/alauda.c
> +++ b/drivers/usb/storage/alauda.c
> @@ -813,6 +813,8 @@ static int alauda_write_lba(struct us_data *us, u16 lba,
>  	unsigned char ecc[3];
>  	int i, result;
>  	unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
> +	if (!uzonesize)
> +		return USB_STOR_TRANSPORT_ERROR;

Check after the list of variables please, not in the middle of them.  I
think checkpatch will complain about this, right?


>  	unsigned int zonesize = MEDIA_INFO(us).zonesize;
>  	unsigned int pagesize = MEDIA_INFO(us).pagesize;
>  	unsigned int blocksize = MEDIA_INFO(us).blocksize;
> @@ -921,6 +923,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
>  	unsigned int blocksize = MEDIA_INFO(us).blocksize;
>  	unsigned int pagesize = MEDIA_INFO(us).pagesize;
>  	unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
> +	if (!uzonesize)
> +		return USB_STOR_TRANSPORT_ERROR;

Same here, at the end of the variable list please.

thanks,

greg k-h

Re: [PATCH v2] usb-storage: Check whether divisor is non-zero before division

[shichao lai]

On Thu, May 23, 2024 at 7:47 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Thu, May 23, 2024 at 07:34:10PM +0800, Shichao Lai wrote:
> > Since uzonesize may be zero, so judgements for non-zero
> > are necessary in both place.
> >
> > Changes since v1:
> > - Add one more check in alauda_write_lba().
> > - Move check ahead of loop in alauda_read_data().
>
> Nit, this changes list should go below the --- line, as the
> documentation asks for.

Sorry for my inexperience. I have read the document and found some
examples but I am still a little confused about this.
I guess this is what you mean?

Since uzonesize may be zero ... (context)

Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yue sun <samsun1006219@gmail.com>
Signed-off-by: Shichao Lai <shichaorai@gmail.com>
---
Changes since v1:
- Add one more check in alauda_write_lba().
- Move check ahead of loop in alauda_read_data().

 drivers/usb/storage/alauda.c | 4 ++++
 1 file changed, 4 insertions(+)
...



> Check after the list of variables please, not in the middle of them.  I
> think checkpatch will complain about this, right?

In fact this script doesn't warn about these problems, but I will
adjust my code style later.
But the check in alauda_write_lba() is due to some variable like
lba_offset and zone will perform modulo and divide operations,
which may throw divide errors when uzonesize is 0.
So I think I prefer to adjust the order of the variable list later.
Changes like this.
```c
unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
unsigned int zonesize = MEDIA_INFO(us).zonesize;
unsigned int pagesize = MEDIA_INFO(us).pagesize;
unsigned int blocksize = MEDIA_INFO(us).blocksize;
unsigned int new_pba_offset;
if (!uzonesize)
    return USB_STOR_TRANSPORT_ERROR;
unsigned int lba_offset = lba % uzonesize;
unsigned int zone = lba / uzonesize;
```
If it's ok, I will post the patch v3 soon.

Re: [PATCH v2] usb-storage: Check whether divisor is non-zero before division

[Greg KH]

On Thu, May 23, 2024 at 08:23:57PM +0800, shichao lai wrote:
> On Thu, May 23, 2024 at 7:47 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Thu, May 23, 2024 at 07:34:10PM +0800, Shichao Lai wrote:
> > > Since uzonesize may be zero, so judgements for non-zero
> > > are necessary in both place.
> > >
> > > Changes since v1:
> > > - Add one more check in alauda_write_lba().
> > > - Move check ahead of loop in alauda_read_data().
> >
> > Nit, this changes list should go below the --- line, as the
> > documentation asks for.
> 
> Sorry for my inexperience. I have read the document and found some
> examples but I am still a little confused about this.
> I guess this is what you mean?
> 
> Since uzonesize may be zero ... (context)
> 
> Reported-by: xingwei lee <xrivendell7@gmail.com>
> Reported-by: yue sun <samsun1006219@gmail.com>
> Signed-off-by: Shichao Lai <shichaorai@gmail.com>
> ---
> Changes since v1:
> - Add one more check in alauda_write_lba().
> - Move check ahead of loop in alauda_read_data().

Yes.

> 
>  drivers/usb/storage/alauda.c | 4 ++++
>  1 file changed, 4 insertions(+)
> ...
> 
> 
> 
> > Check after the list of variables please, not in the middle of them.  I
> > think checkpatch will complain about this, right?
> 
> In fact this script doesn't warn about these problems, but I will
> adjust my code style later.
> But the check in alauda_write_lba() is due to some variable like
> lba_offset and zone will perform modulo and divide operations,
> which may throw divide errors when uzonesize is 0.
> So I think I prefer to adjust the order of the variable list later.
> Changes like this.
> ```c
> unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
> unsigned int zonesize = MEDIA_INFO(us).zonesize;
> unsigned int pagesize = MEDIA_INFO(us).pagesize;
> unsigned int blocksize = MEDIA_INFO(us).blocksize;
> unsigned int new_pba_offset;
> if (!uzonesize)
>     return USB_STOR_TRANSPORT_ERROR;
> unsigned int lba_offset = lba % uzonesize;
> unsigned int zone = lba / uzonesize;
> ```
> If it's ok, I will post the patch v3 soon.

That works, thanks!

greg k-h