From da1ea35fea67ad841f4ada28dd61b41be65e5437 Mon Sep 17 00:00:00 2001 From: Tao Yu Date: Wed, 19 Aug 2026 15:28:35 +0800 Subject: drm/gud: validate TV mode names before creating enum property The GUD protocol returns TV mode names as fixed-size GUD_CONNECTOR_TV_MODE_NAME_LEN entries and requires each name to be NUL-terminated. gud_connector_add_tv_mode() currently passes each fixed-size entry directly to drm_mode_create_tv_properties_legacy(), which eventually reaches drm_property_add_enum() and strlen(). If a device returns an entry without a terminating NUL byte, strlen() reads past the end of the slot and can run beyond the allocated buffer, triggering an out-of-bounds read. Validate that each returned TV mode name contains a NUL terminator within its fixed-size slot before passing it to the DRM property code. If a malformed entry is found, reject the device response with -EIO. This fixes the out-of-bounds read without changing the handling of valid devices, and avoids silently truncating malformed protocol data. Reported-by: syzbot+9ae8e7884e451eaed5b4@syzkaller.appspotmail.com Fixes: 40e1a70b4aed ("drm: Add GUD USB Display driver") Signed-off-by: Tao Yu Reviewed-by: Ruben Wauters Cc: Signed-off-by: Ruben Wauters Link: https://patch.msgid.link/20260819072835.4074130-1-tao1.yu@intel.com --- drivers/gpu/drm/gud/gud_connector.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/gud/gud_connector.c b/drivers/gpu/drm/gud/gud_connector.c index 5c0065c876a7..8141c3a1e30a 100644 --- a/drivers/gpu/drm/gud/gud_connector.c +++ b/drivers/gpu/drm/gud/gud_connector.c @@ -399,8 +399,11 @@ static int gud_connector_add_tv_mode(struct gud_device *gdrm, struct drm_connect for (i = 0; i < num_modes; i++) { char *mode = &buf[i * GUD_CONNECTOR_TV_MODE_NAME_LEN]; - /* The device is not trusted to NUL-terminate the name */ - mode[GUD_CONNECTOR_TV_MODE_NAME_LEN - 1] = '\0'; + if (!memchr(mode, '\0', GUD_CONNECTOR_TV_MODE_NAME_LEN)) { + ret = -EIO; + goto free; + } + modes[i] = mode; } -- cgit v1.2.3