[PATCH v4 02/14] drm/panic: Test address from kmap op for NULL

[Thomas Zimmermann <tzimmermann@suse.de>]

Do nothing if kmap_local_page_try_from_panic() returns NULL. This is
not likely to hapen, as the previous page from the same memory area
has been mapped successfully.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 23437509a694 ("drm/panic: Fix 24bit pixel crossing page boundaries")
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.18+
---
 drivers/gpu/drm/drm_panic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
index ba21df4be338..d28ce8878e05 100644
--- a/drivers/gpu/drm/drm_panic.c
+++ b/drivers/gpu/drm/drm_panic.c
@@ -178,6 +178,8 @@ static void drm_panic_write_pixel24_xpage(void *vaddr, struct page *next_page,
 	u8 *p = vaddr + offset;
 
 	vaddr2 = kmap_local_page_try_from_panic(next_page);
+	if (!vaddr2)
+		return;
 
 	*p++ = color & 0xff;
 	color >>= 8;
-- 
2.55.0