Re: [PATCH v1] binfmt_misc: fix crash when load/unload module

[Andrew Morton]

On Mon, 24 Jan 2022 19:40:53 +0800 kernel test robot <lkp@xxxxxxxxx> wrote:

> Hi Tong,
> 
> 
> >> fs/binfmt_misc.c:828:21: error: incompatible pointer types assigning to 'struct ctl_table_header *' from 'struct sysctl_header *' [-Werror,-Wincompatible-pointer-types]
>            binfmt_misc_header = register_sysctl_mount_point("fs/binfmt_misc");
>                               ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    1 error generated.
> 
> 
> vim +828 fs/binfmt_misc.c
> 
>    821	
>    822	static int __init init_misc_binfmt(void)
>    823	{
>    824		int err = register_filesystem(&bm_fs_type);
>    825		if (!err)
>    826			insert_binfmt(&misc_format);
>    827	
>  > 828		binfmt_misc_header = register_sysctl_mount_point("fs/binfmt_misc");
>    829		if (!binfmt_misc_header) {
>    830			pr_warn("Failed to create fs/binfmt_misc sysctl mount point");
>    831			return -ENOMEM;
>    832		}
>    833		return 0;
>    834	}
>    835	

This is actually a blooper in Luis's "sysctl: add helper to register a
sysctl mount point".

Please test, review, ridicule, etc:

From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: include/linux/sysctl.h: fix register_sysctl_mount_point() return type

The CONFIG_SYSCTL=n stub returns the wrong type.

Fixes: ee9efac48a082 ("sysctl: add helper to register a sysctl mount point")
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Tong Zhang <ztong0001@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 include/linux/sysctl.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/sysctl.h~a
+++ a/include/linux/sysctl.h
@@ -265,7 +265,7 @@ static inline struct ctl_table_header *r
 	return NULL;
 }
 
-static inline struct sysctl_header *register_sysctl_mount_point(const char *path)
+static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
 {
 	return NULL;
 }
_