iommu: apple-dart: fix potential null pointer deref

If kzalloc() fails, accessing cfg->supports_bypass causes a null pointer dereference.

Fix by checking for NULL immediately after allocation and returning -ENOMEM.

Fixes: 3bc0102835f6 ("iommu: apple-dart: Allow mismatched bypass support")
Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://lore.kernel.org/r/20250314230102.11008-1-qasdev00@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 13ccb801f52a4d34f6653f78e92787af7dfed1bc..e13501541fdd9dd23cc24d6424ab8dbc34f5841a 100644 (file)
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -797,12 +797,11 @@ static int apple_dart_of_xlate(struct device *dev,
 
        if (!cfg) {
                cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
-
+               if (!cfg)
+                       return -ENOMEM;
                /* Will be ANDed with DART capabilities */
                cfg->supports_bypass = true;
        }
-       if (!cfg)
-               return -ENOMEM;
        dev_iommu_priv_set(dev, cfg);
 
        cfg_dart = cfg->stream_maps[0].dart;