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

From: Jason Gunthorpe <jgg@ziepe.ca>
To: Tony Lindgren <tony@atomide.com>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Drew Fustini <dfustini@baylibre.com>, Suman Anna <s-anna@ti.com>,
	iommu@lists.linux-foundation.org,
	linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org,
	Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: [PATCH] iommu/omap: Fix regression in probe for NULL pointer dereference
Date: Thu, 31 Mar 2022 11:55:43 -0300	[thread overview]
Message-ID: <20220331145543.GN64706@ziepe.ca> (raw)
In-Reply-To: <20220331062301.24269-1-tony@atomide.com>

On Thu, 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@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@baylibre.com>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Cc: Suman Anna <s-anna@ti.com>
> Suggested-by: Jason Gunthorpe <jgg@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@atomide.com>
> ---
>  drivers/iommu/omap-iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason