On 14/04/2021 17:12, Krzysztof Kozlowski wrote:
> The driver can be matched by legacy platform way or OF-device matching.
> In the first case, of_match_node() can return NULL, which immediately
> would be dereferenced to get the match data.
>
> Addresses-Coverity: Dereference null return value
> Fixes: cd1b00eb24b0 ("mmc: sdhci-s3c: Add device tree support")
> Signed-off-by: Krzysztof Kozlowski <[email protected]>
> ---
>
> Not tested on HW, but the code should be equivalent (plus safer).
>
> drivers/mmc/host/sdhci-s3c.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-s3c.c b/drivers/mmc/host/sdhci-s3c.c
> index f48a788a9d3d..8e1dca625620 100644
> --- a/drivers/mmc/host/sdhci-s3c.c
> +++ b/drivers/mmc/host/sdhci-s3c.c
> @@ -20,6 +20,7 @@
> #include <linux/gpio.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_device.h>
> #include <linux/of_gpio.h>
> #include <linux/pm.h>
> #include <linux/pm_runtime.h>
> @@ -461,19 +462,12 @@ static int sdhci_s3c_parse_dt(struct device *dev,
> }
> #endif
>
> -#ifdef CONFIG_OF
> -static const struct of_device_id sdhci_s3c_dt_match[];
> -#endif
> -
> static inline struct sdhci_s3c_drv_data *sdhci_s3c_get_driver_data(
> struct platform_device *pdev)
> {
> #ifdef CONFIG_OF
> - if (pdev->dev.of_node) {
> - const struct of_device_id *match;
> - match = of_match_node(sdhci_s3c_dt_match, pdev->dev.of_node);
Now I have second thoughts whether NULL pointer can actually happen. If
device is matched via platform/board files, maybe the pdev->dev.of_node
will be NULL thus skipping this branch?
Could there be a case where device is matched via platform_device_id()
(which has different name than compatible!) and (pdev->dev.of_node) is
still assigned? Maybe in case of out of tree DTS?
Anyway, the patch makes the code simpler/smaller, so I still think it is
reasonable. Just the severity of issue is questionable...
Best regards,
Krzysztof
On 14.04.2021 17:25, Krzysztof Kozlowski wrote:
> On 14/04/2021 17:12, Krzysztof Kozlowski wrote:
>> The driver can be matched by legacy platform way or OF-device matching.
>> In the first case, of_match_node() can return NULL, which immediately
>> would be dereferenced to get the match data.
>>
>> Addresses-Coverity: Dereference null return value
>> Fixes: cd1b00eb24b0 ("mmc: sdhci-s3c: Add device tree support")
>> Signed-off-by: Krzysztof Kozlowski <[email protected]>
>> -#ifdef CONFIG_OF
>> -static const struct of_device_id sdhci_s3c_dt_match[];
>> -#endif
>> -
>> static inline struct sdhci_s3c_drv_data *sdhci_s3c_get_driver_data(
>> struct platform_device *pdev)
>> {
>> #ifdef CONFIG_OF
>> - if (pdev->dev.of_node) {
>> - const struct of_device_id *match;
>> - match = of_match_node(sdhci_s3c_dt_match, pdev->dev.of_node);
>
> Now I have second thoughts whether NULL pointer can actually happen. If
> device is matched via platform/board files, maybe the pdev->dev.of_node
> will be NULL thus skipping this branch?
>
> Could there be a case where device is matched via platform_device_id()
> (which has different name than compatible!) and (pdev->dev.of_node) is
> still assigned? Maybe in case of out of tree DTS?
That seems unlikely, the platform device would need to be initialized
via board file and then its of_node assigned somehow. It doesn't make
much sense to me. We either use board file or dtb to instantiate devices.
> Anyway, the patch makes the code simpler/smaller, so I still think it is
> reasonable. Just the severity of issue is questionable...
Yes, the patch looks good. Similar cleanups are already done in most of
the s3c/s5p/exynos drivers.
--
Thanks,
Sylwester
On 14/04/2021 18:49, Sylwester Nawrocki wrote:
> On 14.04.2021 17:25, Krzysztof Kozlowski wrote:
>> On 14/04/2021 17:12, Krzysztof Kozlowski wrote:
>>> The driver can be matched by legacy platform way or OF-device matching.
>>> In the first case, of_match_node() can return NULL, which immediately
>>> would be dereferenced to get the match data.
>>>
>>> Addresses-Coverity: Dereference null return value
>>> Fixes: cd1b00eb24b0 ("mmc: sdhci-s3c: Add device tree support")
>>> Signed-off-by: Krzysztof Kozlowski <[email protected]>
>
>>> -#ifdef CONFIG_OF
>>> -static const struct of_device_id sdhci_s3c_dt_match[];
>>> -#endif
>>> -
>>> static inline struct sdhci_s3c_drv_data *sdhci_s3c_get_driver_data(
>>> struct platform_device *pdev)
>>> {
>>> #ifdef CONFIG_OF
>>> - if (pdev->dev.of_node) {
>>> - const struct of_device_id *match;
>>> - match = of_match_node(sdhci_s3c_dt_match, pdev->dev.of_node);
>>
>> Now I have second thoughts whether NULL pointer can actually happen. If
>> device is matched via platform/board files, maybe the pdev->dev.of_node
>> will be NULL thus skipping this branch?
>>
>> Could there be a case where device is matched via platform_device_id()
>> (which has different name than compatible!) and (pdev->dev.of_node) is
>> still assigned? Maybe in case of out of tree DTS?
>
> That seems unlikely, the platform device would need to be initialized
> via board file and then its of_node assigned somehow. It doesn't make
> much sense to me. We either use board file or dtb to instantiate devices.
>
>> Anyway, the patch makes the code simpler/smaller, so I still think it is
>> reasonable. Just the severity of issue is questionable...
>
> Yes, the patch looks good. Similar cleanups are already done in most of
> the s3c/s5p/exynos drivers.
Thanks Sylwester, I'll resend with different description.
Best regards,
Krzysztof