The driver is dropping the references taken to the larb devices during probe after successful lookup as well as on errors. This can potentially lead to a use-after-free in case a larb device has not yet been bound to its driver so that the iommu driver probe defers.

Fix this by keeping the references as expected while the iommu driver is bound.

Fixes: 26593928564c ("iommu/mediatek: Add error path for loop of mm_dts_parse") Cc: stable@vger.kernel.org Cc: Yong Wu yong.wu@mediatek.com Acked-by: Robin Murphy robin.murphy@arm.com Signed-off-by: Johan Hovold johan@kernel.org --- drivers/iommu/mtk_iommu.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c index 8d8e85186188..64ce041238fd 100644 --- a/drivers/iommu/mtk_iommu.c +++ b/drivers/iommu/mtk_iommu.c @@ -1213,16 +1213,19 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m }

component_match_add(dev, match, component_compare_dev, &plarbdev->dev); - platform_device_put(plarbdev); }

- if (!frst_avail_smicomm_node) - return -EINVAL; + if (!frst_avail_smicomm_node) { + ret = -EINVAL; + goto err_larbdev_put; + }

pcommdev = of_find_device_by_node(frst_avail_smicomm_node); of_node_put(frst_avail_smicomm_node); - if (!pcommdev) - return -ENODEV; + if (!pcommdev) { + ret = -ENODEV; + goto err_larbdev_put; + } data->smicomm_dev = &pcommdev->dev;

link = device_link_add(data->smicomm_dev, dev, @@ -1230,7 +1233,8 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m platform_device_put(pcommdev); if (!link) { dev_err(dev, "Unable to link %s.\n", dev_name(data->smicomm_dev)); - return -EINVAL; + ret = -EINVAL; + goto err_larbdev_put; } return 0;

@@ -1402,8 +1406,12 @@ static int mtk_iommu_probe(struct platform_device *pdev) iommu_device_sysfs_remove(&data->iommu); out_list_del: list_del(&data->list); - if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM)) + if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM)) { device_link_remove(data->smicomm_dev, dev); + + for (i = 0; i < MTK_LARB_NR_MAX; i++) + put_device(data->larb_imu[i].dev); + } out_runtime_disable: pm_runtime_disable(dev); return ret; @@ -1423,6 +1431,9 @@ static void mtk_iommu_remove(struct platform_device *pdev) if (MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM)) { device_link_remove(data->smicomm_dev, &pdev->dev); component_master_del(&pdev->dev, &mtk_iommu_com_ops); + + for (i = 0; i < MTK_LARB_NR_MAX; i++) + put_device(data->larb_imu[i].dev); } pm_runtime_disable(&pdev->dev); for (i = 0; i < data->plat_data->banks_num; i++) {