The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 37801a36b4d68892ce807264f784d818f8d0d39b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024040538-clip-legwarmer-18fc@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

37801a36b4d6 ("selinux: avoid dereference of garbage after mount failure") cd2bb4cb0996 ("selinux: mark some global variables __ro_after_init") db478cd60d55 ("selinux: make selinuxfs_mount static")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 37801a36b4d68892ce807264f784d818f8d0d39b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= cgzones@googlemail.com Date: Thu, 28 Mar 2024 20:16:58 +0100 Subject: [PATCH] selinux: avoid dereference of garbage after mount failure MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c index 0619a1cbbfbe..074d6c2714eb 100644 --- a/security/selinux/selinuxfs.c +++ b/security/selinux/selinuxfs.c @@ -2123,7 +2123,6 @@ 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) @@ -2145,18 +2144,21 @@ 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;