Subject: Re: [PATCH] soc: fsl: qe: Fix potential NULL pointer dereference in qe_reset()

From: "Christophe Leroy (CS GROUP)" <[email-masked]>
Date: Fri, 13 Mar 2026 10:48:54 +0100

Le 10/03/2026 à 13:11, Wang Jun a écrit :
> [Vous ne recevez pas souvent de courriers de [email-masked]. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> The function qe_reset() uses qe_immr without checking if it is NULL,
> which could happen if ioremap() failed earlier. Add a NULL check and
> perform ioremap() if needed; if it still fails, print an error and
> return to avoid crashing the system.

I don't understand what you are trying to say here. What you say is 
already what qe_reset() does: it does a NULL check and performs 
ioremap() when it is NULL:

	if (qe_immr == NULL)
		qe_immr = ioremap(get_qe_base(), QE_IMMAP_SIZE);

You are adding a second NULL check and return early from qe_reset(). But 
it doesn't really fix the problem because qe_immr is used in many other 
places so you are just delaying the problem.

What needs to be done is that if qe_immr remap fails, all drivers 
depending on it don't get probed.

> 
> Signed-off-by: Wang Jun <[email-masked]>
> ---
>   drivers/soc/fsl/qe/qe.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/fsl/qe/qe.c b/drivers/soc/fsl/qe/qe.c
> index 70b6eddb867b..6dcfa340970a 100644
> --- a/drivers/soc/fsl/qe/qe.c
> +++ b/drivers/soc/fsl/qe/qe.c
> @@ -86,8 +86,13 @@ static phys_addr_t get_qe_base(void)
> 
>   void qe_reset(void)
>   {
> -       if (qe_immr == NULL)
> +       if (qe_immr == NULL) {
>                  qe_immr = ioremap(get_qe_base(), QE_IMMAP_SIZE);
> +               if (qe_immr == NULL) {
> +                       pr_err("QE: cannot remap IMMR\n");
> +                       return;
> +               }
> +       }
> 
>          qe_snums_init();
> 
> --
> 2.43.0
>