From: Shang XiaoJing <shangxiaojing@huawei.com>
To: <miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>,
<zev@bewilderbeest.net>, <linux-mtd@lists.infradead.org>
Cc: <shangxiaojing@huawei.com>
Subject: [PATCH] mtd: core: Fix ERROR of refcount due to del_mtd_device()
Date: Sat, 19 Nov 2022 14:39:15 +0800 [thread overview]
Message-ID: <20221119063915.11108-1-shangxiaojing@huawei.com> (raw)
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>
---
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 18aa54460d36..74b1a1c61b39 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -774,6 +774,7 @@ 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);
@@ -792,6 +793,7 @@ 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 */
@@ -803,7 +805,7 @@ 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;
--
2.17.1
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next reply other threads:[~2022-11-19 6:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-19 6:39 Shang XiaoJing [this message]
2022-11-24 11:36 ` [PATCH] mtd: core: Fix ERROR of refcount due to del_mtd_device() Miquel Raynal
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