[PATCH 6.12.y] drm/panic: Do not use un-escaped URL as format string

[Sasha Levin <sashal@kernel.org>]

From: Thomas Zimmermann <tzimmermann@suse.de>

[ Upstream commit 6596aae25585b183ebd528206bde6f12efaf8db1 ]

Replace the direct use of DRM_PANIC_SCREEN_QR_CODE_URL in snprintf()
with a %s conversion specifier. Avoids a possible vulnerabilty from
a crafted URL string.

As the attacker needs to control the kernel at the Kconfig level, the
potential for an exploit is likely low.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Fixes: cb5164ac43d0 ("drm/panic: Add a QR code panic screen")
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.12+
Link: https://patch.msgid.link/20260911124540.279841-2-tzimmermann@suse.de
[ sashal: Retained the zl= URL parameter instead of z= to match the older QR encoding. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/drm_panic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
index 06f0aa1cb4f74..f4662f88e2173 100644
--- a/drivers/gpu/drm/drm_panic.c
+++ b/drivers/gpu/drm/drm_panic.c
@@ -507,7 +507,8 @@ static int drm_panic_get_qr_code_url(u8 **qr_image)
 	char *kmsg;
 	int max_qr_data_size, url_len;
 
-	url_len = snprintf(url, sizeof(url), CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL "?a=%s&v=%s&zl=",
+	url_len = snprintf(url, sizeof(url), "%s?a=%s&v=%s&zl=",
+			   CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL,
 			   utsname()->machine, utsname()->release);
 
 	max_qr_data_size = drm_panic_qr_max_data_size(panic_qr_version, url_len);
-- 
2.53.0