[PATCH next] vfio/xe: Fix use after free in xe_vfio_pci_alloc_file()

[Dan Carpenter <dan.carpenter@linaro.org>]

This code frees "migf" and then dereferences it on the next line to get
the error code.  Preserve the error code before freeing the pointer.

Fixes: 2e38c50ae492 ("vfio/xe: Add device specific vfio_pci driver variant for Intel graphics")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/vfio/pci/xe/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/xe/main.c b/drivers/vfio/pci/xe/main.c
index 0156b53c678b..8e1595e00e18 100644
--- a/drivers/vfio/pci/xe/main.c
+++ b/drivers/vfio/pci/xe/main.c
@@ -250,6 +250,7 @@ xe_vfio_pci_alloc_file(struct xe_vfio_pci_core_device *xe_vdev,
 	struct xe_vfio_pci_migration_file *migf;
 	const struct file_operations *fops;
 	int flags;
+	int ret;
 
 	migf = kzalloc(sizeof(*migf), GFP_KERNEL_ACCOUNT);
 	if (!migf)
@@ -259,8 +260,9 @@ xe_vfio_pci_alloc_file(struct xe_vfio_pci_core_device *xe_vdev,
 	flags = type == XE_VFIO_FILE_SAVE ? O_RDONLY : O_WRONLY;
 	migf->filp = anon_inode_getfile("xe_vfio_mig", fops, migf, flags);
 	if (IS_ERR(migf->filp)) {
+		ret = PTR_ERR(migf->filp);
 		kfree(migf);
-		return ERR_CAST(migf->filp);
+		return ERR_PTR(ret);
 	}
 
 	mutex_init(&migf->lock);
-- 
2.51.0