[v2] i2c: busses/i2c-pxa.c: fix potential null pointer dereference error
diff mbox

Message ID 20130205000517.GB9969@gmail.com
State Changes Requested
Headers show

Commit Message

Cong Ding Feb. 5, 2013, 12:05 a.m. UTC
If it goes to eclk through line 1107, the variable res would be NULL. It will
cause a null pointer dereference error if we call release_mem_region.

Signed-off-by: Cong Ding <dinggnu@gmail.com>
---
 drivers/i2c/busses/i2c-pxa.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Haojian Zhuang Feb. 5, 2013, 1:14 a.m. UTC | #1
On Tue, Feb 5, 2013 at 8:05 AM, Cong Ding <dinggnu@gmail.com> wrote:
> If it goes to eclk through line 1107, the variable res would be NULL. It will
> cause a null pointer dereference error if we call release_mem_region.
>
> Signed-off-by: Cong Ding <dinggnu@gmail.com>
> ---
>  drivers/i2c/busses/i2c-pxa.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index 1034d93..00df535 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -1211,7 +1211,8 @@ eremap:
>  eclk:
>         kfree(i2c);
>  emalloc:
> -       release_mem_region(res->start, resource_size(res));
> +       if (res)
> +               release_mem_region(res->start, resource_size(res));
>         return ret;
>  }
>
>

No. I don't agree on this. Your fix can't resolve all potential issues.

        i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
        if (!i2c) {
                ret = -ENOMEM;
                goto emalloc;
        }

        ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
        if (ret > 0)
                ret = i2c_pxa_probe_pdata(dev, i2c, &i2c_type);
        if (ret < 0)
                goto eclk;

        res = platform_get_resource(dev, IORESOURCE_MEM, 0);
        irq = platform_get_irq(dev, 0);
        if (res == NULL || irq < 0) {
                ret = -ENODEV;
                goto eclk;
        }

        if (!request_mem_region(res->start, resource_size(res), res->name)) {
                ret = -ENOMEM;
                goto eclk;
        }

We shouldn't jump to eclk for these error cases. Then we needn't to add
checking on res.

Regards
Haojian
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Cong Ding Feb. 5, 2013, 10:25 a.m. UTC | #2
On Tue, Feb 05, 2013 at 09:14:08AM +0800, Haojian Zhuang wrote:
> On Tue, Feb 5, 2013 at 8:05 AM, Cong Ding <dinggnu@gmail.com> wrote:
> > If it goes to eclk through line 1107, the variable res would be NULL. It will
> > cause a null pointer dereference error if we call release_mem_region.
> >
> > Signed-off-by: Cong Ding <dinggnu@gmail.com>
> > ---
> >  drivers/i2c/busses/i2c-pxa.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> > index 1034d93..00df535 100644
> > --- a/drivers/i2c/busses/i2c-pxa.c
> > +++ b/drivers/i2c/busses/i2c-pxa.c
> > @@ -1211,7 +1211,8 @@ eremap:
> >  eclk:
> >         kfree(i2c);
> >  emalloc:
> > -       release_mem_region(res->start, resource_size(res));
> > +       if (res)
> > +               release_mem_region(res->start, resource_size(res));
> >         return ret;
> >  }
> >
> >
> 
> No. I don't agree on this. Your fix can't resolve all potential issues.
> 
>         i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
>         if (!i2c) {
>                 ret = -ENOMEM;
>                 goto emalloc;
>         }
> 
>         ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
>         if (ret > 0)
>                 ret = i2c_pxa_probe_pdata(dev, i2c, &i2c_type);
>         if (ret < 0)
>                 goto eclk;
> 
>         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
>         irq = platform_get_irq(dev, 0);
>         if (res == NULL || irq < 0) {
>                 ret = -ENODEV;
>                 goto eclk;
>         }
> 
>         if (!request_mem_region(res->start, resource_size(res), res->name)) {
>                 ret = -ENOMEM;
>                 goto eclk;
>         }
> 
> We shouldn't jump to eclk for these error cases. Then we needn't to add
> checking on res.
So what do you suggest to do for these error cases?
 - cong

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Haojian Zhuang Feb. 5, 2013, 11:27 a.m. UTC | #3
On Tue, Feb 5, 2013 at 6:25 PM, Cong Ding <dinggnu@gmail.com> wrote:
> On Tue, Feb 05, 2013 at 09:14:08AM +0800, Haojian Zhuang wrote:
>> On Tue, Feb 5, 2013 at 8:05 AM, Cong Ding <dinggnu@gmail.com> wrote:
>> > If it goes to eclk through line 1107, the variable res would be NULL. It will
>> > cause a null pointer dereference error if we call release_mem_region.
>> >
>> > Signed-off-by: Cong Ding <dinggnu@gmail.com>
>> > ---
>> >  drivers/i2c/busses/i2c-pxa.c |    3 ++-
>> >  1 file changed, 2 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
>> > index 1034d93..00df535 100644
>> > --- a/drivers/i2c/busses/i2c-pxa.c
>> > +++ b/drivers/i2c/busses/i2c-pxa.c
>> > @@ -1211,7 +1211,8 @@ eremap:
>> >  eclk:
>> >         kfree(i2c);
>> >  emalloc:
>> > -       release_mem_region(res->start, resource_size(res));
>> > +       if (res)
>> > +               release_mem_region(res->start, resource_size(res));
>> >         return ret;
>> >  }
>> >
>> >
>>
>> No. I don't agree on this. Your fix can't resolve all potential issues.
>>
>>         i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL);
devm_kzalloc
>>         if (!i2c) {
>>                 ret = -ENOMEM;
>>                 goto emalloc;
return -ENOMEM;
>>         }
>>
>>         ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
>>         if (ret > 0)
>>                 ret = i2c_pxa_probe_pdata(dev, i2c, &i2c_type);
>>         if (ret < 0)
>>                 goto eclk;
return ret;
>>
>>         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
>>         irq = platform_get_irq(dev, 0);
>>         if (res == NULL || irq < 0) {
>>                 ret = -ENODEV;
>>                 goto eclk;
ditto
>>         }
>>
>>         if (!request_mem_region(res->start, resource_size(res), res->name)) {
>>                 ret = -ENOMEM;
>>                 goto eclk;
ditto
>>         }
>>
>> We shouldn't jump to eclk for these error cases. Then we needn't to add
>> checking on res.
> So what do you suggest to do for these error cases?
>  - cong
>
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Patch
diff mbox

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 1034d93..00df535 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -1211,7 +1211,8 @@  eremap:
 eclk:
 	kfree(i2c);
 emalloc:
-	release_mem_region(res->start, resource_size(res));
+	if (res)
+		release_mem_region(res->start, resource_size(res));
 	return ret;
 }