Commit 5634c8cb authored by Nitin Gote's avatar Nitin Gote Committed by Thomas Zimmermann
Browse files

iosys-map: Fix undefined behavior in iosys_map_clear() 

The current iosys_map_clear() implementation reads the potentially
uninitialized 'is_iomem' boolean field to decide which union member
to clear. This causes undefined behavior when called on uninitialized
structures, as 'is_iomem' may contain garbage values like 0xFF.

UBSAN detects this as:
    UBSAN: invalid-load in include/linux/iosys-map.h:267
    load of value 255 is not a valid value for type '_Bool'

Fix by unconditionally clearing the entire structure with memset(),
eliminating the need to read uninitialized data and ensuring all
fields are set to known good values.

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14639


Fixes: 01fd30da ("dma-buf: Add struct dma-buf-map for storing struct dma_buf.vaddr_ptr")
Signed-off-by: default avatarNitin Gote <nitin.r.gote@intel.com>
Reviewed-by: default avatarAndi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250718105051.2709487-1-nitin.r.gote@intel.com
parent 05663d88

include/linux/iosys-map.h

+1 −6
Original line number Diff line number Diff line
@@ -264,12 +264,7 @@ static inline bool iosys_map_is_set(const struct iosys_map *map) 
 */

static inline void iosys_map_clear(struct iosys_map *map)

{

	if (map->is_iomem) {

		map->vaddr_iomem = NULL;

		map->is_iomem = false;

	} else {

		map->vaddr = NULL;

	}

	memset(map, 0, sizeof(*map));

}



/**