iio: potentiometer: ds1803: remove VLA usage

PATCH In review Gustavo A. R. Silva 2 participants 6 messages Mar 13, 2018 IIO

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Gustavo A. R. Silva

author

2018-03-13 15:23 UTC #0 lore raw

PATCH 1/1 iio: potentiometer: ds1803: remove VLA usage

In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _result_ can be computed at preprocessing time.

The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug.

Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/iio/potentiometer/ds1803.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/iio/potentiometer/ds1803.c +1 -1

index 9b0ff4a..6bf12c9 100644
@@ -64,7 +64,7 @@ static int ds1803_read_raw(struct iio_dev *indio_dev,
 	struct ds1803_data *data = iio_priv(indio_dev);
 	int pot = chan->channel;
 	int ret;
-	u8 result[indio_dev->num_channels];
+	u8 result[ARRAY_SIZE(ds1803_channels)];
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:

Signature · 1 line

2.7.4

Himanshu Jha

2018-03-13 16:24 UTC #1 lore raw

Hi Gustavo,

Quoted 10 lines · Gustavo A. R. Silva

In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _result_ can be computed at preprocessing time.
The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug.

Quoted 5 lines

Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621
Signed-off-by Gustavo A. R. Silva <[email protected]>
---

It is already applied as I had sent the patch few days ago.
https://lkml.org/lkml/2018/3/10/164

I specifically CC'ed you and Kees to avoid the patch collisions.

Signature · 2 lines

Thanks
Himanshu Jha

Gustavo A. R. Silva

author

2018-03-13 16:31 UTC #2 lore raw

Quoted 16 lines · Himanshu Jha

Hi Gustavo,
Quoted 13 lines · Gustavo A. R. Silva
In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _result_ can be computed at preprocessing time.
The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug.
Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621

Quoted 8 lines

Quoted 2 lines
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
It is already applied as I had sent the patch few days ago.
https://lkml.org/lkml/2018/3/10/164
I specifically CC'ed you and Kees to avoid the patch collisions.

I see. Can you please update this spreadsheet:

https://docs.google.com/spreadsheets/d/1OcfyKK8pJ24esYhSEsW4Q2boZE7UTGbYsSEEtFXf7U0/edit

Thanks
--
Gustavo

Himanshu Jha

2018-03-13 16:59 UTC #3 lore raw

Quoted 25 lines · Gustavo A. R. Silva

Quoted 22 lines · Himanshu Jha
Hi Gustavo,
Quoted 10 lines · Gustavo A. R. Silva
In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _result_ can be computed at preprocessing time.
The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug.
Quoted 5 lines
Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
It is already applied as I had sent the patch few days ago.
https://lkml.org/lkml/2018/3/10/164

Quoted 6 lines

Quoted 2 lines
I specifically CC'ed you and Kees to avoid the patch collisions.
I see. Can you please update this spreadsheet:
https://docs.google.com/spreadsheets/d/1OcfyKK8pJ24esYhSEsW4Q2boZE7UTGbYsSEEtFXf7U0/edit

Updated!

Also,

drivers/iio/humidity/hts221_i2c.c:43:2: warning: ISO C90 forbids variable length array ‘send’ [-Wvla]

This was already removed in recent commit when regmap API was used.

"6217792 iio: humidity: hts221: add regmap API support"

For this I added a short note in the *Notes* column.

Signature · 2 lines

Thanks
Himanshu Jha

Gustavo A. R. Silva

author

2018-03-13 17:05 UTC #4 lore raw

Quoted 37 lines · Himanshu Jha

Quoted 25 lines · Gustavo A. R. Silva
Quoted 22 lines · Himanshu Jha
Hi Gustavo,
Quoted 10 lines · Gustavo A. R. Silva
In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _result_ can be computed at preprocessing time.
The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug.
Quoted 5 lines
Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
It is already applied as I had sent the patch few days ago.
https://lkml.org/lkml/2018/3/10/164
Quoted 6 lines
Quoted 2 lines
I specifically CC'ed you and Kees to avoid the patch collisions.
I see. Can you please update this spreadsheet:
https://docs.google.com/spreadsheets/d/1OcfyKK8pJ24esYhSEsW4Q2boZE7UTGbYsSEEtFXf7U0/edit
Updated!
Also,

Quoted 9 lines

drivers/iio/humidity/hts221_i2c.c:43:2: warning: ISO C90 forbids variable length array ‘send’ [-Wvla]
This was already removed in recent commit when regmap API was used.
"6217792 iio: humidity: hts221: add regmap API support"
For this I added a short note in the *Notes* column.

Awesome.

Thank you
--
Gustavo

Gustavo A. R. Silva

author

2018-03-13 17:07 UTC #5 lore raw

In reply to Himanshu Jha

Quoted 37 lines · Himanshu Jha

Quoted 25 lines · Gustavo A. R. Silva
Quoted 22 lines · Himanshu Jha
Hi Gustavo,
Quoted 10 lines · Gustavo A. R. Silva
In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _result_ can be computed at preprocessing time.
The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug.
Quoted 5 lines
Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
It is already applied as I had sent the patch few days ago.
https://lkml.org/lkml/2018/3/10/164
Quoted 6 lines
Quoted 2 lines
I specifically CC'ed you and Kees to avoid the patch collisions.
I see. Can you please update this spreadsheet:
https://docs.google.com/spreadsheets/d/1OcfyKK8pJ24esYhSEsW4Q2boZE7UTGbYsSEEtFXf7U0/edit
Updated!
Also,

Quoted 9 lines

drivers/iio/humidity/hts221_i2c.c:43:2: warning: ISO C90 forbids variable length array ‘send’ [-Wvla]
This was already removed in recent commit when regmap API was used.
"6217792 iio: humidity: hts221: add regmap API support"
For this I added a short note in the *Notes* column.

Awesome.

Thank you
--
Gustavo