From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6D35D3054D8; Tue, 2 Sep 2025 13:24:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756819446; cv=none; b=babJNhh7TJjKJ/eFiXTHCNZ9HXABY+pVY1SosCDVvRia8pG8PNd3Y7GsbTsq7+QVGc6bOOJZzLlVo3mpSBW5WGq5Tce6U4q1dGEDBYZl4MPqjb3KDwKlAeANgZ43A5g3+ZTrFiXTRsL3ySZqXT0l6HQ1yMfkmCIcf2U00Afhc78= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756819446; c=relaxed/simple; bh=beNxsUH1B9xG4UHXbxZUoKfUXi2l/udl82QdBlkrLSM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WRj60Ze3MSNeck6Nh0KvQ3NpzNIm62lUN9j+o2ucRYEbXSO59uCUERPZG84pG0t4GJv8GdzKGJFCVxZ9K1ahnWLupnU0W/mio+c5bZKFi3xiYPOvkW+JLPSFLIoLALyhztzekLO5t+ZGp2h+ubH3dOPMhv5LhmSjEVk3UDkc02s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0gkbK18F; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0gkbK18F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D50E8C4CEED; Tue, 2 Sep 2025 13:24:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756819446; bh=beNxsUH1B9xG4UHXbxZUoKfUXi2l/udl82QdBlkrLSM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0gkbK18FfvKbqgigmG2f5vOEgZTHf+GdoAGLstOk7cdDDuv269jIwb7Mc4NizYb+a GvUxtqowqYkNDp5uY++HNDQr4LX/m6pZIxKDix2eqKht7oBeQgwsZa82sjVGiPZ/2N S8QBV2QU26U8OMk17j15F+hZkxWDxMwCX3Ue48oU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jason-JH Lin , AngeloGioacchino Del Regno , CK Hu , Chun-Kuang Hu , Sasha Levin Subject: [PATCH 6.16 037/142] drm/mediatek: Add error handling for old state CRTC in atomic_disable Date: Tue, 2 Sep 2025 15:18:59 +0200 Message-ID: <20250902131949.569648429@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250902131948.154194162@linuxfoundation.org> References: <20250902131948.154194162@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason-JH Lin [ Upstream commit 0c6b24d70da21201ed009a2aca740d2dfddc7ab5 ] Introduce error handling to address an issue where, after a hotplug event, the cursor continues to update. This situation can lead to a kernel panic due to accessing the NULL `old_state->crtc`. E,g. Unable to handle kernel NULL pointer dereference at virtual address Call trace: mtk_crtc_plane_disable+0x24/0x140 mtk_plane_atomic_update+0x8c/0xa8 drm_atomic_helper_commit_planes+0x114/0x2c8 drm_atomic_helper_commit_tail_rpm+0x4c/0x158 commit_tail+0xa0/0x168 drm_atomic_helper_commit+0x110/0x120 drm_atomic_commit+0x8c/0xe0 drm_atomic_helper_update_plane+0xd4/0x128 __setplane_atomic+0xcc/0x110 drm_mode_cursor_common+0x250/0x440 drm_mode_cursor_ioctl+0x44/0x70 drm_ioctl+0x264/0x5d8 __arm64_sys_ioctl+0xd8/0x510 invoke_syscall+0x6c/0xe0 do_el0_svc+0x68/0xe8 el0_svc+0x34/0x60 el0t_64_sync_handler+0x1c/0xf8 el0t_64_sync+0x180/0x188 Adding NULL pointer checks to ensure stability by preventing operations on an invalid CRTC state. Fixes: d208261e9f7c ("drm/mediatek: Add wait_event_timeout when disabling plane") Signed-off-by: Jason-JH Lin Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20250728025036.24953-1-jason-jh.lin@mediatek.com/ Signed-off-by: Chun-Kuang Hu Signed-off-by: Sasha Levin --- drivers/gpu/drm/mediatek/mtk_plane.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/mediatek/mtk_plane.c b/drivers/gpu/drm/mediatek/mtk_plane.c index cbc4f37da8ba8..02349bd440017 100644 --- a/drivers/gpu/drm/mediatek/mtk_plane.c +++ b/drivers/gpu/drm/mediatek/mtk_plane.c @@ -292,7 +292,8 @@ static void mtk_plane_atomic_disable(struct drm_plane *plane, wmb(); /* Make sure the above parameter is set before update */ mtk_plane_state->pending.dirty = true; - mtk_crtc_plane_disable(old_state->crtc, plane); + if (old_state && old_state->crtc) + mtk_crtc_plane_disable(old_state->crtc, plane); } static void mtk_plane_atomic_update(struct drm_plane *plane, -- 2.50.1