linux-kernel - Re: [PATCH 1/2] SELinux: Fix lsm_get_self

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Date: Fri, 23 Feb 2024 20:16:51 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Casey Schaufler <casey@...aufler-ca.com>, 
	John Johansen <john.johansen@...onical.com>, Paul Moore <paul@...l-moore.com>
Cc: James Morris <jmorris@...ei.org>, 
	"Serge E . Hallyn" <serge@...lyn.com>, linux-kernel@...r.kernel.org, 
	linux-security-module@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/2] SELinux: Fix lsm_get_self_attr()

These bugs have been found with syzkaller. I just sent a PR to add
support for the new LSM syscalls:
https://github.com/google/syzkaller/pull/4524


On Fri, Feb 23, 2024 at 08:05:45PM +0100, Mickaël Salaün wrote:
> selinux_lsm_getattr() may not initialize the value's pointer in some
> case.  As for proc_pid_attr_read(), initialize this pointer to NULL in
> selinux_getselfattr() to avoid an UAF in the kfree() call.
> 
> Cc: Casey Schaufler <casey@...aufler-ca.com>
> Cc: Paul Moore <paul@...l-moore.com>
> Cc: stable@...r.kernel.org
> Fixes: 762c934317e6 ("SELinux: Add selfattr hooks")
> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
> ---
>  security/selinux/hooks.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index a6bf90ace84c..338b023a8c3e 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6559,7 +6559,7 @@ static int selinux_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
>  			       size_t *size, u32 flags)
>  {
>  	int rc;
> -	char *val;
> +	char *val = NULL;
>  	int val_len;
>  
>  	val_len = selinux_lsm_getattr(attr, current, &val);
> -- 
> 2.43.0
>