Re: [PATCH v2] drm/omap: dsi: do not copy isr table

[Andreas Kemnade]

On Thu, Jul 02, 2026 at 05:27:11PM +0200, Andreas Kemnade wrote:
> To te able to unregister stuff from isrs, the corresponding table was
> copied.  Nobody seems to unregister stuff that way, so it does not help.
> But there are stack-allocated objects passed to these isrs giving chances
> of UAF of these objects if irqs are unregistered while they are handled,
> so better do not copy that table.
> 
> Fixes: 4ae2ddddf44cd ("OMAP: DSS2: DSI: Add ISR support")
> Signed-off-by: Andreas Kemnade <andreas@xxxxxxxxxxxx>

a friendly ping... the corresponding fix in the old fb code already was
accepted.

Regards,
Andreas

> ---
> If this gets backported, it should be re-checked that
> no isr unregisters itself in older kernel versions`.
> ---
> Changes in v2:
> - remove variable definition (Sashiko)
> - Link to v1: https://patch.msgid.link/20260629-dsi-uaf-v1-1-a5e894f4e4d1@xxxxxxxxxxxx
> 
> To: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> To: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> To: Maxime Ripard <mripard@xxxxxxxxxx>
> To: Thomas Zimmermann <tzimmermann@xxxxxxx>
> To: David Airlie <airlied@xxxxxxxxx>
> To: Simona Vetter <simona@xxxxxxxx>
> Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  drivers/gpu/drm/omapdrm/dss/dsi.c | 7 +------
>  drivers/gpu/drm/omapdrm/dss/dsi.h | 2 --
>  2 files changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> index 27fe7bca9e2c..70cfb779d6ae 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> @@ -455,15 +455,10 @@ static irqreturn_t omap_dsi_irq_handler(int irq, void *arg)
>  		timer_delete(&dsi->te_timer);
>  #endif
>  
> -	/* make a copy and unlock, so that isrs can unregister
> -	 * themselves */
> -	memcpy(&dsi->isr_tables_copy, &dsi->isr_tables,
> -		sizeof(dsi->isr_tables));
> +	dsi_handle_isrs(&dsi->isr_tables, irqstatus, vcstatus, ciostatus);
>  
>  	spin_unlock(&dsi->irq_lock);
>  
> -	dsi_handle_isrs(&dsi->isr_tables_copy, irqstatus, vcstatus, ciostatus);
> -
>  	dsi_handle_irq_errors(dsi, irqstatus, vcstatus, ciostatus);
>  
>  	dsi_collect_irq_stats(dsi, irqstatus, vcstatus, ciostatus);
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.h b/drivers/gpu/drm/omapdrm/dss/dsi.h
> index 601707c0ecc4..2b25247ea893 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.h
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.h
> @@ -379,8 +379,6 @@ struct dsi_data {
>  
>  	spinlock_t irq_lock;
>  	struct dsi_isr_tables isr_tables;
> -	/* space for a copy used by the interrupt handler */
> -	struct dsi_isr_tables isr_tables_copy;
>  
>  	int update_vc;
>  #ifdef DSI_PERF_MEASURE
> 
> ---
> base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
> change-id: 20260629-dsi-uaf-71bfbf3553bf
> 
> Best regards,
> --  
> Andreas Kemnade <andreas@xxxxxxxxxxxx>
> 
>