[PATCH 6.1.y] selinux: avoid dereference of garbage after mount failure

jianqi.ren.cn
2025-05-12T01:44:14Z

From: Christian Göttsche <cgzones@googlemail.com>

commit 37801a36b4d68892ce807264f784d818f8d0d39b upstream.

In case kern_mount() fails and returns an error pointer return in the
error branch instead of continuing and dereferencing the error pointer.

While on it drop the never read static variable selinuxfs_mount.

Cc: stable@vger.kernel.org
Fixes: 0619f0f5e36f ("selinux: wrap selinuxfs state")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
---
Verified the build test
---
security/selinux/selinuxfs.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index ab804d4ea911..c236f3cd2dd7 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -2210,7 +2210,6 @@ static struct file_system_type sel_fs_type = {
.kill_sb = sel_kill_sb,
};

-static struct vfsmount *selinuxfs_mount __ro_after_init;
struct path selinux_null __ro_after_init;

static int __init init_sel_fs(void)
@@ -2232,18 +2231,21 @@ static int __init init_sel_fs(void)
return err;
}

- selinux_null.mnt = selinuxfs_mount = kern_mount(&sel_fs_type);
- if (IS_ERR(selinuxfs_mount)) {
+ selinux_null.mnt = kern_mount(&sel_fs_type);
+ if (IS_ERR(selinux_null.mnt)) {
pr_err("selinuxfs: could not mount!\n");
- err = PTR_ERR(selinuxfs_mount);
- selinuxfs_mount = NULL;
+ err = PTR_ERR(selinux_null.mnt);
+ selinux_null.mnt = NULL;
+ return err;
}
+
selinux_null.dentry = d_hash_and_lookup(selinux_null.mnt->mnt_root,
&null_name);
if (IS_ERR(selinux_null.dentry)) {
pr_err("selinuxfs: could not lookup null!\n");
err = PTR_ERR(selinux_null.dentry);
selinux_null.dentry = NULL;
+ return err;
}

return err;
--
2.34.1