From 500cb24cd61bad8a2747ddfc49b7034899c82d94 Mon Sep 17 00:00:00 2001 From: Deepanshu Kartikey Date: Sun, 16 Aug 2026 14:22:34 +0530 Subject: [PATCH] drm/gud: NUL-terminate TV mode names read from the device gud_connector_add_tv_mode() reads a buffer of fixed-size mode names from the USB device and passes pointers into it to drm_mode_create_tv_properties_legacy(), which calls strlen() on each one. Nothing guarantees the device NUL-terminates a name, so strlen() can run past the end of a slot and, for the last mode, past the end of the allocation. Terminate each name at the end of its slot before use. Fixes: 40e1a70b4aed ("drm: Add GUD USB Display driver") Reported-by: syzbot+916c888ba5f1a54c9526@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=916c888ba5f1a54c9526 Tested-by: syzbot+916c888ba5f1a54c9526@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey Acked-by: Ruben Wauters Cc: Signed-off-by: Ruben Wauters Link: https://patch.msgid.link/20260816085234.22053-1-kartikey406@gmail.com --- drivers/gpu/drm/gud/gud_connector.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/gud/gud_connector.c b/drivers/gpu/drm/gud/gud_connector.c index ea0cca58b7c8..5c0065c876a7 100644 --- a/drivers/gpu/drm/gud/gud_connector.c +++ b/drivers/gpu/drm/gud/gud_connector.c @@ -396,8 +396,13 @@ static int gud_connector_add_tv_mode(struct gud_device *gdrm, struct drm_connect } num_modes = ret / GUD_CONNECTOR_TV_MODE_NAME_LEN; - for (i = 0; i < num_modes; i++) - modes[i] = &buf[i * GUD_CONNECTOR_TV_MODE_NAME_LEN]; + 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'; + modes[i] = mode; + } ret = drm_mode_create_tv_properties_legacy(connector->dev, num_modes, modes); free: