[PATCH] mtd: Fix device name leak when register device failed in add_mtd_device()

[PATCH] mtd: Fix device name leak when register device failed in add_mtd_device()

[Zhang Xiaoxu]

There is a kmemleak when register device failed:
  unreferenced object 0xffff888101aab550 (size 8):
    comm "insmod", pid 3922, jiffies 4295277753 (age 925.408s)
    hex dump (first 8 bytes):
      6d 74 64 30 00 88 ff ff                          mtd0....
    backtrace:
      [<00000000bde26724>] __kmalloc_node_track_caller+0x4e/0x150
      [<000000003c32b416>] kvasprintf+0xb0/0x130
      [<000000001f7a8f15>] kobject_set_name_vargs+0x2f/0xb0
      [<000000006e781163>] dev_set_name+0xab/0xe0
      [<00000000e30d0c78>] add_mtd_device+0x4bb/0x700
      [<00000000f3d34de7>] mtd_device_parse_register+0x2ac/0x3f0
      [<00000000c0d88488>] 0xffffffffa0238457
      [<00000000b40d0922>] 0xffffffffa02a008f
      [<0000000023d17b9d>] do_one_initcall+0x87/0x2a0
      [<00000000770f6ca6>] do_init_module+0xdf/0x320
      [<000000007b6768fe>] load_module+0x2f98/0x3330
      [<00000000346bed5a>] __do_sys_finit_module+0x113/0x1b0
      [<00000000674c2290>] do_syscall_64+0x35/0x80
      [<000000004c6a8d97>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

If register device failed, should call put_device() to give up the
reference.

Fixes: 1f24b5a8ecbb ("[MTD] driver model updates")
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@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..f4858310331c 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -723,8 +723,10 @@ int add_mtd_device(struct mtd_info *mtd)
 	mtd_check_of_node(mtd);
 	of_node_get(mtd_get_of_node(mtd));
 	error = device_register(&mtd->dev);
-	if (error)
+	if (error) {
+		put_device(&mtd->dev);
 		goto fail_added;
+	}
 
 	/* Add the nvmem provider */
 	error = mtd_nvmem_add(mtd);
-- 
2.31.1


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Re: [PATCH] mtd: Fix device name leak when register device failed in add_mtd_device()

[Miquel Raynal]

On Sat, 2022-10-22 at 12:13:52 UTC, Zhang Xiaoxu wrote:
> There is a kmemleak when register device failed:
>   unreferenced object 0xffff888101aab550 (size 8):
>     comm "insmod", pid 3922, jiffies 4295277753 (age 925.408s)
>     hex dump (first 8 bytes):
>       6d 74 64 30 00 88 ff ff                          mtd0....
>     backtrace:
>       [<00000000bde26724>] __kmalloc_node_track_caller+0x4e/0x150
>       [<000000003c32b416>] kvasprintf+0xb0/0x130
>       [<000000001f7a8f15>] kobject_set_name_vargs+0x2f/0xb0
>       [<000000006e781163>] dev_set_name+0xab/0xe0
>       [<00000000e30d0c78>] add_mtd_device+0x4bb/0x700
>       [<00000000f3d34de7>] mtd_device_parse_register+0x2ac/0x3f0
>       [<00000000c0d88488>] 0xffffffffa0238457
>       [<00000000b40d0922>] 0xffffffffa02a008f
>       [<0000000023d17b9d>] do_one_initcall+0x87/0x2a0
>       [<00000000770f6ca6>] do_init_module+0xdf/0x320
>       [<000000007b6768fe>] load_module+0x2f98/0x3330
>       [<00000000346bed5a>] __do_sys_finit_module+0x113/0x1b0
>       [<00000000674c2290>] do_syscall_64+0x35/0x80
>       [<000000004c6a8d97>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> If register device failed, should call put_device() to give up the
> reference.
> 
> Fixes: 1f24b5a8ecbb ("[MTD] driver model updates")
> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel

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