From: Shang XiaoJing shangxiaojing@huawei.com
[ Upstream commit 56570bdad5e31c5c538cd6efff5c4510256e1bb4 ]
del_mtd_device() will call of_node_put() to mtd_get_of_node(mtd), which is mtd->dev.of_node. However, memset(&mtd->dev, 0) is called before of_node_put(). As the result, of_node_put() won't do anything in del_mtd_device(), and causes the refcount leak.
del_mtd_device() memset(&mtd->dev, 0, sizeof(mtd->dev) # clear mtd->dev of_node_put() mtd_get_of_node(mtd) # mtd->dev is cleared, can't locate of_node # of_node_put(NULL) won't do anything
Fix the error by caching the pointer of the device_node.
OF: ERROR: memory leak, expected refcount 1 instead of 2, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node /spi/spi-sram@0 CPU: 3 PID: 275 Comm: python3 Tainted: G N 6.1.0-rc3+ #54 0d8a1edddf51f172ff5226989a7565c6313b08e2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x67/0x83 kobject_get+0x155/0x160 of_node_get+0x1f/0x30 of_fwnode_get+0x43/0x70 fwnode_handle_get+0x54/0x80 fwnode_get_nth_parent+0xc9/0xe0 fwnode_full_name_string+0x3f/0xa0 device_node_string+0x30f/0x750 pointer+0x598/0x7a0 vsnprintf+0x62d/0x9b0 ... cfs_overlay_release+0x30/0x90 config_item_release+0xbe/0x1a0 config_item_put+0x5e/0x80 configfs_rmdir+0x3bd/0x540 vfs_rmdir+0x18c/0x320 do_rmdir+0x198/0x330 __x64_sys_rmdir+0x2c/0x40 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: 00596576a051 ("mtd: core: clear out unregistered devices a bit more") Signed-off-by: Shang XiaoJing shangxiaojing@huawei.com [miquel.raynal@bootlin.com: Light reword of the commit log] Signed-off-by: Miquel Raynal miquel.raynal@bootlin.com Link: https://lore.kernel.org/linux-mtd/20221119063915.11108-1-shangxiaojing@huawe... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mtd/mtdcore.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 37050c551880..c14196bbf008 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -776,6 +776,7 @@ int del_mtd_device(struct mtd_info *mtd) { int ret; struct mtd_notifier *not; + struct device_node *mtd_of_node;
mutex_lock(&mtd_table_mutex);
@@ -794,6 +795,7 @@ int del_mtd_device(struct mtd_info *mtd) mtd->index, mtd->name, mtd->usecount); ret = -EBUSY; } else { + mtd_of_node = mtd_get_of_node(mtd); debugfs_remove_recursive(mtd->dbg.dfs_dir);
/* Try to remove the NVMEM provider */ @@ -805,7 +807,7 @@ int del_mtd_device(struct mtd_info *mtd) memset(&mtd->dev, 0, sizeof(mtd->dev));
idr_remove(&mtd_idr, mtd->index); - of_node_put(mtd_get_of_node(mtd)); + of_node_put(mtd_of_node);
module_put(THIS_MODULE); ret = 0;