[PATCH] drm/komeda: Handle NULL pointer access code path in error case

From: carsten.haitzler@foss.arm.com
To: dri-devel@lists.freedesktop.org
Cc: liviu.dudau@arm.com, Carsten Haitzler <carsten.haitzler@arm.com>
Subject: [PATCH] drm/komeda: Handle NULL pointer access code path in error case
Date: Fri, 27 Nov 2020 11:00:54 +0000	[thread overview]
Message-ID: <20201127110054.133686-1-carsten.haitzler@foss.arm.com> (raw)

From: Carsten Haitzler <carsten.haitzler@arm.com>

komeda_component_get_old_state() technically can return a NULL
pointer. komeda_compiz_set_input() even warns when this happens, but
then proceeeds to use that NULL pointer tocompare memory content there
agains the new sate to see if it changed. In this case, it's better to
assume that the input changed as there is no old state to compare
against and thus assume the changes happen anyway.

Signed-off-by: Carsten Haitzler <carsten.haitzler@arm.com>
---
 drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
index 8f32ae7c25d0..e8b1e15312d8 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
@@ -707,7 +707,8 @@ komeda_compiz_set_input(struct komeda_compiz *compiz,
 	WARN_ON(!old_st);
 
 	/* compare with old to check if this input has been changed */
-	if (memcmp(&(to_compiz_st(old_st)->cins[idx]), cin, sizeof(*cin)))
+	if (!old_st ||
+	    memcmp(&(to_compiz_st(old_st)->cins[idx]), cin, sizeof(*cin)))
 		c_st->changed_active_inputs |= BIT(idx);
 
 	komeda_component_add_input(c_st, &dflow->input, idx);
-- 
2.29.2

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