[PATCH] iommu/omap: Fix regression in probe for NULL pointer dereference

[Drew Fustini]

On TLhu, Mar 31, 2022 at 09:23:01AM +0300, Tony Lindgren wrote:
> Commit 3f6634d997db ("iommu: Use right way to retrieve iommu_ops") started
> triggering a NULL pointer dereference for some omap variants:
> 
> __iommu_probe_device from probe_iommu_group+0x2c/0x38
> probe_iommu_group from bus_for_each_dev+0x74/0xbc
> bus_for_each_dev from bus_iommu_probe+0x34/0x2e8
> bus_iommu_probe from bus_set_iommu+0x80/0xc8
> bus_set_iommu from omap_iommu_init+0x88/0xcc
> omap_iommu_init from do_one_initcall+0x44/0x24
> 
> This is caused by omap iommu probe returning 0 instead of ERR_PTR(-ENODEV)
> as noted by Jason Gunthorpe <jgg at ziepe.ca>.
> 
> Looks like the regression already happened with an earlier commit
> 6785eb9105e3 ("iommu/omap: Convert to probe/release_device() call-backs")
> that changed the function return type and missed converting one place.
> 
> Cc: Drew Fustini <dfustini at baylibre.com>
> Cc: Lu Baolu <baolu.lu at linux.intel.com>
> Cc: Suman Anna <s-anna at ti.com>
> Suggested-by: Jason Gunthorpe <jgg at ziepe.ca>
> Fixes: 6785eb9105e3 ("iommu/omap: Convert to probe/release_device() call-backs")
> Fixes: 3f6634d997db ("iommu: Use right way to retrieve iommu_ops")
> Signed-off-by: Tony Lindgren <tony at atomide.com>
> ---
>  drivers/iommu/omap-iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
> --- a/drivers/iommu/omap-iommu.c
> +++ b/drivers/iommu/omap-iommu.c
> @@ -1661,7 +1661,7 @@ static struct iommu_device *omap_iommu_probe_device(struct device *dev)
>  	num_iommus = of_property_count_elems_of_size(dev->of_node, "iommus",
>  						     sizeof(phandle));
>  	if (num_iommus < 0)
> -		return 0;
> +		return ERR_PTR(-ENODEV);
>  
>  	arch_data = kcalloc(num_iommus + 1, sizeof(*arch_data), GFP_KERNEL);
>  	if (!arch_data)
> -- 
> 2.35.1

Mainline with omap2plus_defconfig now boots ok on my BeagleBoard-X15
with the TI AM5728 SoC after this patch is applied.

Tested-by: Drew Fustini <dfustini at baylibre.com>

thanks,
drew