[U-Boot] [PATCH] mmc: sdhci: fix NULL pointer access when host->ops is not set

[Jaehoon Chung]

Hi,

On 01/13/2017 11:51 AM, Masahiro Yamada wrote:
> Until recently, sdhci_ops was used only for overriding IO accessors.
> (so, host->ops was not set by any drivers except bcm2835_sdhci.c)
> 
> Now, we have more optional callbacks, get_cd, set_control_reg, and
> set_clock.  However, the code
> 
>     if (host->ops->get_cd)
>             host->ops->get_cd(host);
> 
> ... expects host->ops is set for all drivers.
> 
> Commit 5e96217f0434 ("mmc: pic32_sdhci: move the code to
> pic32_sdhci.c") and commit 62226b68631b ("mmc: sdhci: move the
> callback function into sdhci_ops") added sdhci_ops for pic32_sdhci.c
> and s5p_sdhci.c, but the other drivers still do not (need not) set
> host->ops because all callbacks in sdhci_ops are optional.
> 
> host->ops must be checked to avoid the system crash caused by NULL
> pointer access.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>

Thanks a lot! Applied on u-boot-mmc.

Best Regards,
Jaehoon Chung

> ---
> 
>  drivers/mmc/sdhci.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
> index 3a1f4f7..5b404ff 100644
> --- a/drivers/mmc/sdhci.c
> +++ b/drivers/mmc/sdhci.c
> @@ -359,7 +359,7 @@ static int sdhci_set_clock(struct mmc *mmc, unsigned int clock)
>  		div >>= 1;
>  	}
>  
> -	if (host->ops->set_clock)
> +	if (host->ops && host->ops->set_clock)
>  		host->ops->set_clock(host, div);
>  
>  	clk |= (div & SDHCI_DIV_MASK) << SDHCI_DIVIDER_SHIFT;
> @@ -427,7 +427,7 @@ static int sdhci_set_ios(struct mmc *mmc)
>  	u32 ctrl;
>  	struct sdhci_host *host = mmc->priv;
>  
> -	if (host->ops->set_control_reg)
> +	if (host->ops && host->ops->set_control_reg)
>  		host->ops->set_control_reg(host);
>  
>  	if (mmc->clock != host->clock)
> @@ -480,7 +480,7 @@ static int sdhci_init(struct mmc *mmc)
>  
>  	sdhci_set_power(host, fls(mmc->cfg->voltages) - 1);
>  
> -	if (host->ops->get_cd)
> +	if (host->ops && host->ops->get_cd)
>  		host->ops->get_cd(host);
>  
>  	/* Enable only interrupts served by the SD controller */
>