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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Drew Fustini <dfustini@baylibre.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Suman Anna <s-anna@ti.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Tony Lindgren <tony@atomide.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Joerg Roedel <jroedel@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 208/285] iommu/omap: Fix regression in probe for NULL pointer dereference
Date:   Tue, 12 Apr 2022 08:31:05 +0200
Message-Id: <20220412062949.662554328@linuxfoundation.org>
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From: Tony Lindgren <tony@atomide.com>

[ Upstream commit 71ff461c3f41f6465434b9e980c01782763e7ad8 ]

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>
Tested-by: Drew Fustini <dfustini@baylibre.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220331062301.24269-1-tony@atomide.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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
index 91749654fd49..be60f6f3a265 100644
--- 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