2020-12-22 08:51:37

by Md Sadre Alam

Subject: [PATCH] mmc: sdhci-msm: Fix possible NULL pointer exception

of_device_get_match_data returns NULL when no match.
So add the NULL pointer check to avoid dereference.

Signed-off-by: Md Sadre Alam <[email protected]>
---
drivers/mmc/host/sdhci-msm.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index 9c7927b..f20e424 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -2235,6 +2235,8 @@ static int sdhci_msm_probe(struct platform_device *pdev)
* the data associated with the version info.
*/
var_info = of_device_get_match_data(&pdev->dev);
+ if (!var_info)
+ goto pltfm_free;

msm_host->mci_removed = var_info->mci_removed;
msm_host->restore_dll_config = var_info->restore_dll_config;
--
2.7.4

2020-12-31 06:44:50

by Veerabhadrarao Badiganti

Subject: Re: [PATCH] mmc: sdhci-msm: Fix possible NULL pointer exception

On 12/22/2020 2:18 PM, Md Sadre Alam wrote:
> of_device_get_match_data returns NULL when no match.
> So add the NULL pointer check to avoid dereference.
>
> Signed-off-by: Md Sadre Alam <[email protected]>
> ---

Reviewed-by: Veerabhadrarao Badiganti <[email protected]>

> drivers/mmc/host/sdhci-msm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 9c7927b..f20e424 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -2235,6 +2235,8 @@ static int sdhci_msm_probe(struct platform_device *pdev)
> * the data associated with the version info.
> */
> var_info = of_device_get_match_data(&pdev->dev);
> + if (!var_info)
> + goto pltfm_free;
>
> msm_host->mci_removed = var_info->mci_removed;
> msm_host->restore_dll_config = var_info->restore_dll_config;

2021-01-05 14:43:30

by Adrian Hunter

Subject: Re: [PATCH] mmc: sdhci-msm: Fix possible NULL pointer exception

On 22/12/20 10:48 am, Md Sadre Alam wrote:
> of_device_get_match_data returns NULL when no match.
> So add the NULL pointer check to avoid dereference.
>
> Signed-off-by: Md Sadre Alam <[email protected]>
> ---
> drivers/mmc/host/sdhci-msm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 9c7927b..f20e424 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -2235,6 +2235,8 @@ static int sdhci_msm_probe(struct platform_device *pdev)
> * the data associated with the version info.
> */
> var_info = of_device_get_match_data(&pdev->dev);
> + if (!var_info)

Shouldn't you set ret to -ENODEV here?

> + goto pltfm_free;
>
> msm_host->mci_removed = var_info->mci_removed;
> msm_host->restore_dll_config = var_info->restore_dll_config;
>

2021-01-05 22:27:17

by Bjorn Andersson

Subject: Re: [PATCH] mmc: sdhci-msm: Fix possible NULL pointer exception

On Tue 22 Dec 02:48 CST 2020, Md Sadre Alam wrote:

> of_device_get_match_data returns NULL when no match.
> So add the NULL pointer check to avoid dereference.
>
> Signed-off-by: Md Sadre Alam <[email protected]>
> ---
> drivers/mmc/host/sdhci-msm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 9c7927b..f20e424 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -2235,6 +2235,8 @@ static int sdhci_msm_probe(struct platform_device *pdev)
> * the data associated with the version info.
> */
> var_info = of_device_get_match_data(&pdev->dev);
> + if (!var_info)

To get this you (the SDHCI driver developer) needs to add an entry in
sdhci_msm_dt_match[] without a .data specified.

> + goto pltfm_free;

And this will cause sdhci_msm_probe() to return 0, giving no hint to
said developer that they screwed up. Given that this can only be caused
by a developer working on this driver you should provide feedback
suitable for such developer, e.g. by:

if (WARN_ON(!var_info))
return -EINVAL;

But given that this is only for the developer himself, I don't see that
this adds any value over just reading the callstack you get from the
panic when the next line dereferences var_info (NULL).

Regards,
Bjorn

>
> msm_host->mci_removed = var_info->mci_removed;
> msm_host->restore_dll_config = var_info->restore_dll_config;
> --
> 2.7.4
>