Messages in this thread Patch in this message | | | From | Alexander Usyskin <> | Subject | [PATCH] mtd: fix use-after-free in mtd release | Date | Thu, 27 Jul 2023 17:57:58 +0300 |
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I case of partition device_unregister in mtd_device_release calls mtd_release which frees mtd_info structure for partition. All code after device_unregister in mtd_device_release thus works already freed memory.
Move part of code to mtd_release and restict mtd->dev cleanup to non-partion object. For partition object such cleanup have no sense as partition mtd_info is removed.
Cc: Miquel Raynal <miquel.raynal@bootlin.com> Cc: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Fixes: 19bfa9ebebb5 ("mtd: use refcount to prevent corruption") Reviewed-by: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com> --- drivers/mtd/mtdcore.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 2466ea466466..46f15f676491 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -93,6 +93,9 @@ static void mtd_release(struct device *dev) struct mtd_info *mtd = dev_get_drvdata(dev); dev_t index = MTD_DEVT(mtd->index); + idr_remove(&mtd_idr, mtd->index); + of_node_put(mtd_get_of_node(mtd)); + if (mtd_is_partition(mtd)) release_mtd_partition(mtd); @@ -103,6 +106,7 @@ static void mtd_release(struct device *dev) static void mtd_device_release(struct kref *kref) { struct mtd_info *mtd = container_of(kref, struct mtd_info, refcnt); + bool is_partition = mtd_is_partition(mtd); debugfs_remove_recursive(mtd->dbg.dfs_dir); @@ -111,11 +115,13 @@ static void mtd_device_release(struct kref *kref) device_unregister(&mtd->dev); - /* Clear dev so mtd can be safely re-registered later if desired */ - memset(&mtd->dev, 0, sizeof(mtd->dev)); - - idr_remove(&mtd_idr, mtd->index); - of_node_put(mtd_get_of_node(mtd)); + /* + * Clear dev so mtd can be safely re-registered later if desired. + * Should not be done for partition, + * as it was already destroyed in device_unregister(). + */ + if (!is_partition) + memset(&mtd->dev, 0, sizeof(mtd->dev)); module_put(THIS_MODULE); } -- 2.34.1
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