From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Wentao Liang <vulab@iscas.ac.cn>,
	Alex Deucher <alexander.deucher@amd.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15.y 2/2] drm/amd/display: Fix dc stream excess put in dm_update_crtc_state()
Date: Tue, 29 Sep 2026 14:46:13 -0400
Message-ID: <20260929184613.521461-2-sashal@kernel.org>
In-Reply-To: <20260929184613.521461-1-sashal@kernel.org>
References: <2026092930-shrubs-hankering-0ed0@gregkh>
 <20260929184613.521461-1-sashal@kernel.org>
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From: Wentao Liang <vulab@iscas.ac.cn>

[ Upstream commit c5fd4eaad50d620c7e09ac2082b2fb55ee54170e ]

In dm_update_crtc_state(), when a modeset is required the newly created
stream is stored in dm_new_crtc_state->stream and an extra reference is
taken with dc_stream_retain().  The reference returned by
create_validate_stream_for_sink() is released as an extra reference at
the skip_modeset label, leaving the stream owned by the new CRTC state.

If amdgpu_dm_check_crtc_color_mgmt() fails afterwards, the code jumps
to the fail label which releases new_stream again.  Since the extra
reference was already released at skip_modeset, this drops the
reference owned by dm_new_crtc_state->stream and the stream is
released while the atomic state still points to it, leading to a
premature free of the dc stream.

Set new_stream to NULL after releasing the extra reference at the
skip_modeset label so that a later goto fail cannot release the
reference owned by the new CRTC state.

Fixes: 7cd4b70091a5 ("drm/amd/display: Rework CRTC color management")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 102a47065a62dc8f6bbbb47cf082a2934282eb08)
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

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 7d628393415da..6478036a025f0 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -10482,8 +10482,10 @@ static int dm_update_crtc_state(struct amdgpu_display_manager *dm,
 
 skip_modeset:
 	/* Release extra reference */
-	if (new_stream)
+	if (new_stream) {
 		dc_stream_release(new_stream);
+		new_stream = NULL;
+	}
 	new_stream = NULL;
 
 	/*
-- 
2.53.0