[PATCH] drm/panel: novatek-nt36536: Fix panel double-remove on attach failure

[PATCH] drm/panel: novatek-nt36536: Fix panel double-remove on attach failure

[David Carlier]

The DSI attach error path calls drm_panel_remove() by hand even though
the panel was registered with devm_drm_panel_add(), which already
arranges for drm_panel_remove() to run on driver detach. When
mipi_dsi_attach() fails the panel is therefore removed twice: once
directly and once again while devres unwinds.

drm_panel_add() takes a reference and drm_panel_remove() drops one, so
the extra removal releases the last reference early and frees the panel
container. The put registered by devm_drm_panel_alloc() then operates on
freed memory, resulting in a use-after-free and a reference-count
underflow when a DSI host rejects the requested configuration during
probe.

Drop the manual drm_panel_remove() and let the managed cleanup handle
it, matching the other dual-DSI panel drivers.

Fixes: 75a5dbd1f4f7 ("drm/panel: Add Novatek NT36536 panel driver")
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 drivers/gpu/drm/panel/panel-novatek-nt36536.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt36536.c b/drivers/gpu/drm/panel/panel-novatek-nt36536.c
index 2a82b54880c3..8bd125650168 100644
--- a/drivers/gpu/drm/panel/panel-novatek-nt36536.c
+++ b/drivers/gpu/drm/panel/panel-novatek-nt36536.c
@@ -429,11 +429,9 @@ static int novatek_probe(struct mipi_dsi_device *dsi)
 		ctx->dsi[i]->mode_flags = desc->mode_flags;
 		ctx->dsi[i]->dsc = &ctx->dsc;
 		ret = devm_mipi_dsi_attach(dev, ctx->dsi[i]);
-		if (ret < 0) {
-			drm_panel_remove(&ctx->panel);
+		if (ret < 0)
 			return dev_err_probe(dev, ret,
 					     "Failed to attach to DSI host\n");
-		}
 	}
 
 	if (desc->has_dcs_backlight) {
-- 
2.53.0