Patch "selinux: avoid dereference of garbage after mount failure" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selinux: avoid dereference of garbage after mount failure

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selinux-avoid-dereference-of-garbage-after-mount-fai.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 6d98c3c1fef632225f341c91f898f704c513a416
Author: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
Date:   Thu Mar 28 20:16:58 2024 +0100

    selinux: avoid dereference of garbage after mount failure
    
    [ Upstream commit 37801a36b4d68892ce807264f784d818f8d0d39b ]
    
    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@xxxxxxxxxxxxxxx
    Fixes: 0619f0f5e36f ("selinux: wrap selinuxfs state")
    Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
    Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index f2f6203e0fff5..a96895d8bb6d7 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -2208,7 +2208,6 @@ 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)
@@ -2230,18 +2229,21 @@ 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;