On Thu, Jan 16, 2025 at 2:55 PM Ingyu Jang <ingyujang25@xxxxxxxxx> wrote:
>
> The 'selinux_inode' function may return NULL if 'inode->i_security' is
> uninitialized or if 'inode->i_security' is NULL.
> Previously, this scenario was not explicitly handled in
> 'inode_security_rcu', which might lead to NULL Pointer dereference.
>
> This patch modifies 'inode_security_rcu' to call 'selinux_inode' and
> check its return value.
> If 'selinux_inode' returns NULL, '-EACCES' is returned to ensure
> consistent error handling.
>
> Furthermore, analysis confirmed that all current usages of
> 'inode_security_rcu' check the return value using 'IS_ERR', ensuring
> compatibility with this change.
>
> Signed-off-by: Ingyu Jang <ingyujang25@xxxxxxxxx>
Do you have an actual example where this is currently possible if
SELinux is enabled?
It shouldn't be possible, so that would be a kernel bug that should be fixed.
> ---
> security/selinux/hooks.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 171dd7fceac5..61c9191bafbe 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -310,11 +310,17 @@ static struct inode_security_struct *inode_security_novalidate(struct inode *ino
> static struct inode_security_struct *inode_security_rcu(struct inode *inode, bool rcu)
> {
> int error;
> + struct inode_security_struct *isec;
>
> error = __inode_security_revalidate(inode, NULL, !rcu);
> if (error)
> return ERR_PTR(error);
> - return selinux_inode(inode);
> +
> + isec = selinux_inode(inode);
> + if (!isec)
> + return ERR_PTR(-EACCES);
> +
> + return isec;
> }
>
> /*
> --
> 2.34.1
>
