In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and
array 'offset_array' of size 5 can lead to a buffer overflow, since the index
'bank' can have an out of range value 63.
Fix this bug by limiting top index value.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller")
Signed-off-by: Aleksandr Mishin <[email protected]>
---
drivers/gpio/gpio-davinci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c
index bb499e362912..b65df1f2b83f 100644
--- a/drivers/gpio/gpio-davinci.c
+++ b/drivers/gpio/gpio-davinci.c
@@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev)
spin_lock_init(&chips->lock);
nbank = DIV_ROUND_UP(ngpio, 32);
+ if (nbank > MAX_REGS_BANKS || nbank > 5) {
+ nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5;
+ }
for (bank = 0; bank < nbank; bank++)
chips->regs[bank] = gpio_base + offset_array[bank];
--
2.30.2
On Thu, Mar 28, 2024 at 12:10:21PM +0300, Aleksandr Mishin wrote:
> In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and
> array 'offset_array' of size 5 can lead to a buffer overflow, since the index
> 'bank' can have an out of range value 63.
^^
Where does this 63 come from? SVACE is a static analysis tool. I would
have thought a static checker would say that 'bank' goes up to
UINT_MAX / 32.
This stuff comes from device tree though, so it looks fine to me.
Documentation/devicetree/bindings/gpio/gpio-davinci.yaml: ti,ngpio = <144>;
Documentation/devicetree/bindings/gpio/gpio-davinci.yaml: ti,ngpio = <32>;
Documentation/devicetree/bindings/gpio/gpio-davinci.yaml: ti,ngpio = <56>;
arch/arm/boot/dts/ti/davinci/da850.dtsi: ti,ngpio = <144>;
So it's fine.
I'm not the maintainer of this file so I don't know if adding a sanity
check makes sense but if we wanted to do that we'd have to add it to
davinci_gpio_get_pdata(). Otherwise it would have already had a buffer
overflow earlier in the probe function when we do:
drivers/gpio/gpio-davinci.c
223 if (pdata->gpio_unbanked)
224 nirq = pdata->gpio_unbanked;
225 else
226 nirq = DIV_ROUND_UP(ngpio, 16);
227
228 chips = devm_kzalloc(dev, sizeof(*chips), GFP_KERNEL);
229 if (!chips)
230 return -ENOMEM;
231
232 gpio_base = devm_platform_ioremap_resource(pdev, 0);
233 if (IS_ERR(gpio_base))
234 return PTR_ERR(gpio_base);
235
236 for (i = 0; i < nirq; i++) {
237 chips->irqs[i] = platform_get_irq(pdev, i);
^^^
238 if (chips->irqs[i] < 0)
239 return chips->irqs[i];
240 }
regards,
dan carpenter
From: Aleksandr Mishin <[email protected]>
Date: Thu, 28 Mar 2024 12:10:21 +0300
> In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and
> array 'offset_array' of size 5 can lead to a buffer overflow, since the index
> 'bank' can have an out of range value 63.
> Fix this bug by limiting top index value.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller")
> Signed-off-by: Aleksandr Mishin <[email protected]>
> ---
> drivers/gpio/gpio-davinci.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c
> index bb499e362912..b65df1f2b83f 100644
> --- a/drivers/gpio/gpio-davinci.c
> +++ b/drivers/gpio/gpio-davinci.c
> @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev)
> spin_lock_init(&chips->lock);
>
> nbank = DIV_ROUND_UP(ngpio, 32);
> + if (nbank > MAX_REGS_BANKS || nbank > 5) {
> + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5;
> + }
Static analysis warnings make no sense until you provide a reliable way
to trigger the problem on real systems.
> for (bank = 0; bank < nbank; bank++)
> chips->regs[bank] = gpio_base + offset_array[bank];
>
Thanks,
Olek
28.03.2024 18:27, Alexander Lobakin пишет:
> From: Aleksandr Mishin <[email protected]>
> Date: Thu, 28 Mar 2024 12:10:21 +0300
>
>> In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and
>> array 'offset_array' of size 5 can lead to a buffer overflow, since the index
>> 'bank' can have an out of range value 63.
>> Fix this bug by limiting top index value.
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller")
>> Signed-off-by: Aleksandr Mishin <[email protected]>
>> ---
>> drivers/gpio/gpio-davinci.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c
>> index bb499e362912..b65df1f2b83f 100644
>> --- a/drivers/gpio/gpio-davinci.c
>> +++ b/drivers/gpio/gpio-davinci.c
>> @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev)
>> spin_lock_init(&chips->lock);
>>
>> nbank = DIV_ROUND_UP(ngpio, 32);
>> + if (nbank > MAX_REGS_BANKS || nbank > 5) {
>> + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5;
>> + }
>
> Static analysis warnings make no sense until you provide a reliable way
> to trigger the problem on real systems.
>
>> for (bank = 0; bank < nbank; bank++)
>> chips->regs[bank] = gpio_base + offset_array[bank];
>>
>
> Thanks,
> Olek
>
I can only see the code at this time. And I see the following:
1. In some configurations CONFIG_ARCH_NR_GPIO value is 2048. So nbank
value can be 64.
2. Previously, a patch was proposed that removes restrictions on the
number of GPIOs
(https://lore.kernel.org/all/cb540a9d73cad36d288664f8b275c6308a4a3168.1662116601.git.christophe.leroy@csgroup.eu/).
--
Kind regards
Aleksandr
From: Aleksandr Mishin <[email protected]>
Date: Thu, 28 Mar 2024 19:23:56 +0300
>
>
> 28.03.2024 18:27, Alexander Lobakin пишет:
>> From: Aleksandr Mishin <[email protected]>
>> Date: Thu, 28 Mar 2024 12:10:21 +0300
>>
>>> In davinci_gpio_probe() accessing an element of array 'chips->regs'
>>> of size 5 and
>>> array 'offset_array' of size 5 can lead to a buffer overflow, since
>>> the index
>>> 'bank' can have an out of range value 63.
>>> Fix this bug by limiting top index value.
>>>
>>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>>
>>> Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of
>>> memory for controller")
>>> Signed-off-by: Aleksandr Mishin <[email protected]>
>>> ---
>>> drivers/gpio/gpio-davinci.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c
>>> index bb499e362912..b65df1f2b83f 100644
>>> --- a/drivers/gpio/gpio-davinci.c
>>> +++ b/drivers/gpio/gpio-davinci.c
>>> @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct
>>> platform_device *pdev)
>>> spin_lock_init(&chips->lock);
>>> nbank = DIV_ROUND_UP(ngpio, 32);
>>> + if (nbank > MAX_REGS_BANKS || nbank > 5) {
>>> + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5;
>>> + }
>>
>> Static analysis warnings make no sense until you provide a reliable way
>> to trigger the problem on real systems.
>>
>>> for (bank = 0; bank < nbank; bank++)
>>> chips->regs[bank] = gpio_base + offset_array[bank];
>>>
>>
>> Thanks,
>> Olek
>>
>
> I can only see the code at this time. And I see the following:
> 1. In some configurations CONFIG_ARCH_NR_GPIO value is 2048. So nbank
> value can be 64.
> 2. Previously, a patch was proposed that removes restrictions on the
> number of GPIOs
> (https://lore.kernel.org/all/cb540a9d73cad36d288664f8b275c6308a4a3168.1662116601.git.christophe.leroy@csgroup.eu/).
>
But no real hardware / device tree which declares such huge number of
GPIOs, right?
CONFIG_ARCH_NR_GPIO is architecture-specific. Davinci is a platform, not
an architecture. If no Davinci board can have a number that would
overflow, the fix doesn't make sense.
Thanks,
Olek
On Thu, Mar 28, 2024 at 04:27:24PM +0100, Alexander Lobakin wrote:
> > diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c
> > index bb499e362912..b65df1f2b83f 100644
> > --- a/drivers/gpio/gpio-davinci.c
> > +++ b/drivers/gpio/gpio-davinci.c
> > @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev)
> > spin_lock_init(&chips->lock);
> >
> > nbank = DIV_ROUND_UP(ngpio, 32);
> > + if (nbank > MAX_REGS_BANKS || nbank > 5) {
> > + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5;
> > + }
>
> Static analysis warnings make no sense until you provide a reliable way
> to trigger the problem on real systems.
This patch isn't correct, but we merge a few static checker fixes every
day.
regards,
dan carpenter