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<p>I think we can ignore this change, as it already exists in the
below commit of asdn.</p>
<p><span><span class="ui-provider a b c d e f g h i j k l m n o p q r s t u v w x y z ab ac ae af ag ah ai aj ak" dir="ltr">commit b90c2f233397f40c757995b9c00f8c6e380c6913<br>
Author: Alex Hung <a class="moz-txt-link-rfc2396E" href="mailto:alex.hung@amd.com"><alex.hung@amd.com></a><br>
Date: Thu Jun 27 17:38:16 2024 -0600
<p></p>
<p> drm/amd/display: Check null pointers before using them</p>
</span></span></p>
<div class="moz-cite-prefix">On 7/17/2024 8:10 AM, Srinivasan
Shanmugam wrote:<br>
</div>
<blockquote type="cite" cite="mid:20240717024000.512972-1-srinivasan.shanmugam@amd.com">
<pre class="moz-quote-pre" wrap="">This commit adds a null check for the dm_state variable in the
create_validate_stream_for_sink function. Previously, dm_state was being
checked for nullity at line 7194, but then it was being dereferenced
without any nullity check at line 7200. This could potentially lead to a
null pointer dereference error if dm_state is indeed null.
we now ensure that dm_state is not null before dereferencing it. We do
this by adding a nullity check for dm_state before the call to
create_stream_for_sink at line 7200. If dm_state is null, we log an
error message and return NULL immediately.
This fix prevents a null pointer dereference error.
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:7201 create_validate_stream_for_sink()
error: we previously assumed 'dm_state' could be null (see line 7194)
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c
7185 struct dc_stream_state *
7186 create_validate_stream_for_sink(struct amdgpu_dm_connector *aconnector,
7187 const struct drm_display_mode *drm_mode,
7188 const struct dm_connector_state *dm_state,
7189 const struct dc_stream_state *old_stream)
7190 {
7191 struct drm_connector *connector = &aconnector->base;
7192 struct amdgpu_device *adev = drm_to_adev(connector->dev);
7193 struct dc_stream_state *stream;
7194 const struct drm_connector_state *drm_state = dm_state ? &dm_state->base : NULL;
^^^^^^^^
^^^^^^^^^ This used check connector->state but then we changed it to dm_state instead
7195 int requested_bpc = drm_state ? drm_state->max_requested_bpc : 8;
7196 enum dc_status dc_result = DC_OK;
7197
7198 do {
7199 stream = create_stream_for_sink(connector, drm_mode,
7200 dm_state, old_stream,
^^^^^^^^
But dm_state is dereferenced on the next line without checking. (Presumably the NULL check can be removed).
--> 7201 requested_bpc);
7202 if (stream == NULL) {
7203 DRM_ERROR("Failed to create stream for sink!\n");
7204 break;
7205 }
7206
7207 if (aconnector->base.connector_type == DRM_MODE_CONNECTOR_WRITEBACK)
Fixes: fa7041d9d2fc ("drm/amd/display: Fix ineffective setting of max bpc property")
Reported-by: Dan Carpenter <a class="moz-txt-link-rfc2396E" href="mailto:dan.carpenter@linaro.org"><dan.carpenter@linaro.org></a>
Cc: Tom Chung <a class="moz-txt-link-rfc2396E" href="mailto:chiahsuan.chung@amd.com"><chiahsuan.chung@amd.com></a>
Cc: Rodrigo Siqueira <a class="moz-txt-link-rfc2396E" href="mailto:Rodrigo.Siqueira@amd.com"><Rodrigo.Siqueira@amd.com></a>
Cc: Roman Li <a class="moz-txt-link-rfc2396E" href="mailto:roman.li@amd.com"><roman.li@amd.com></a>
Cc: Hersen Wu <a class="moz-txt-link-rfc2396E" href="mailto:hersenxs.wu@amd.com"><hersenxs.wu@amd.com></a>
Cc: Alex Hung <a class="moz-txt-link-rfc2396E" href="mailto:alex.hung@amd.com"><alex.hung@amd.com></a>
Cc: Aurabindo Pillai <a class="moz-txt-link-rfc2396E" href="mailto:aurabindo.pillai@amd.com"><aurabindo.pillai@amd.com></a>
Cc: Harry Wentland <a class="moz-txt-link-rfc2396E" href="mailto:harry.wentland@amd.com"><harry.wentland@amd.com></a>
Cc: Hamza Mahfooz <a class="moz-txt-link-rfc2396E" href="mailto:hamza.mahfooz@amd.com"><hamza.mahfooz@amd.com></a>
Signed-off-by: Srinivasan Shanmugam <a class="moz-txt-link-rfc2396E" href="mailto:srinivasan.shanmugam@amd.com"><srinivasan.shanmugam@amd.com></a>
---
v2: s/DRM_ERROR/drm_err() (Hamza)
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index d1527c2e46a1..e7516a2dcb10 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -7195,6 +7195,11 @@ create_validate_stream_for_sink(struct amdgpu_dm_connector *aconnector,
int requested_bpc = drm_state ? drm_state->max_requested_bpc : 8;
enum dc_status dc_result = DC_OK;
+ if (!dm_state) {
+ drm_err(&adev->ddev, "dm_state is NULL!\n");
+ return NULL;
+ }
+
do {
stream = create_stream_for_sink(connector, drm_mode,
dm_state, old_stream,
</pre>
</blockquote>
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