From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9D83EE9A02C for ; Sun, 22 Feb 2026 05:46:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C3D7F10E0D8; Sun, 22 Feb 2026 05:46:20 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; secure) header.d=shenghaoyang.info header.i=@shenghaoyang.info header.b="LX9Wy7s4"; dkim-atps=neutral Received: from mail-pg1-f171.google.com (mail-pg1-f171.google.com [209.85.215.171]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9136B10E0D8 for ; Sun, 22 Feb 2026 05:46:18 +0000 (UTC) Received: by mail-pg1-f171.google.com with SMTP id 41be03b00d2f7-c6e7e3f92adso557882a12.2 for ; Sat, 21 Feb 2026 21:46:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shenghaoyang.info; s=google; t=1771739178; x=1772343978; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=JhKzjTP9AJUfYj/qxi/+hBVU7eETqHo7vcCCz4bDmZU=; b=LX9Wy7s4+jZ2Bk2jvQL1kScnmE5/TMP1eX8MrHuDJWd0/CQsZYoRN7GdSBOQLebt5h BJBoGQkBoAb+NEeTaj65oSZ3DZgVn9iID+HFpdtEv4wBT2CUJSvfHO0gg+eSeIIM5cH0 Vhaox4p+MOjROZ6UABJawYXmAgw4VC0cor1G/KXMLOgLz+Os3w3PClb0N1Cu0S/gYhRV Cuid08/oDj2k6BQHHjrisOY+TjSq3ohOv2Gl4PdUuffr8KBQHhprU7PnOcZbRJfEkgfl p6hzQe9JA0MQNjzZlZNw4XjYH29BhhaoinUiK8vk1vLkeN8stM1+vGn+6WYxatrKlyR1 GDLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771739178; x=1772343978; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=JhKzjTP9AJUfYj/qxi/+hBVU7eETqHo7vcCCz4bDmZU=; b=YJsGrzK3lDv6p9VFMr/RXXXrLiwXoQj4SWC525gYMBDNsJdgdpk/pjdJZ+F3jCbXc0 /UOKXvdcK3MlN/v325dn3W/82MaIJ1FnwAD0K23t2xKG/xc/eUschBAsq2KPUdaKdSI4 APa0HC2Ca6OofftzTv8+kvMujLJ35FD3ljsp4HTURUGmgKLGW+6GwQDoUM2kwkXz3UvG BQHSO20SsGTSCmlO03VGMOoOeM9szv2ndO5DRNY5xaT4zTPpFY3HX3y1qKhlNZHVuUnN 6ceh9xqFPSAGN0HI6kVRzqYT8WXFB8wdu01Zs37LfHuivm3LB7hjWmafq/9SVoNJh3WB ofSg== X-Gm-Message-State: AOJu0YwNG7IudR1AIBMsQqqN6RUlr1tKoc5gtg2yx3FyhRYfu8aInOY4 2KWbiezx2BDcxfl9WtNGkGniANvFMmlfp7A+H1nEifxgOdaui+i3zoXEmC/bAsV84QI= X-Gm-Gg: AZuq6aJU/u9uI2UsvFeJaaI+KiKXdy3L0mwthbUKM04178CbUkB/ZfWYO594gZGfdyi A3iCrc7Nsz+aalNZTHCy/K3AjAY2mHix5Tm+uKeRCLjdZaHzokM8e/all/5NokIR1GaLOLL60SK 0maSwWuiAdSp68yyrcTpMJN+FNb+BK2tMlg5scBx+3zMXYEaPgU1hJjCI59VpYrWmA2qn/72+Mj is0EIRxXU7KJAVhXlnBzmCzw7dS+5EKch/cgN+Vc/+iDBZ+mZdfGoHd4vl7/fbOYqf2XtLAcCh5 yzHjRx6Ku7MmNTbTK/Q/BLqg3Yd7voyLOjBrq9yJPte/Jokf7pAotQQtdOG1sKR8HUz6C1H2zHf jyyE4/Oys73d5iPv48wZyuE2BZIrjoGBoxl4phHr/Io7PErDgCH2rUeP6+Q83GKAUx8H/cG9jkW k4ocAtfOqSgQOGhk6hyOtX X-Received: by 2002:a17:90b:5624:b0:340:bca2:cf82 with SMTP id 98e67ed59e1d1-358ae8a8df2mr3004305a91.4.1771739177810; Sat, 21 Feb 2026 21:46:17 -0800 (PST) Received: from localhost ([132.147.84.99]) by smtp.gmail.com with UTF8SMTPSA id 98e67ed59e1d1-358af71f9a3sm3433129a91.6.2026.02.21.21.46.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 21 Feb 2026 21:46:17 -0800 (PST) From: Shenghao Yang To: Ruben Wauters , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Shenghao Yang , kernel test robot , Dan Carpenter Subject: [PATCH v5] drm/gud: fix NULL crtc dereference on display disable Date: Sun, 22 Feb 2026 13:45:51 +0800 Message-ID: <20260222054551.80864-1-me@shenghaoyang.info> X-Mailer: git-send-email 2.53.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" gud_plane_atomic_update() currently handles both crtc state and framebuffer updates - the complexity has led to a few accidental NULL pointer dereferences. Commit dc2d5ddb193e ("drm/gud: fix NULL fb and crtc dereferences on USB disconnect") [1] fixed an earlier dereference but planes can also be disabled in non-hotplug paths (e.g. display disables via the desktop environment). The drm_dev_enter() call would not cause an early return in those and subsequently oops on dereferencing crtc: BUG: kernel NULL pointer dereference, address: 00000000000005c8 CPU: 6 UID: 1000 PID: 3473 Comm: kwin_wayland Not tainted 6.18.2-200.vanilla.gud.fc42.x86_64 #1 PREEMPT(lazy) RIP: 0010:gud_plane_atomic_update+0x148/0x470 [gud] drm_atomic_helper_commit_planes+0x28e/0x310 drm_atomic_helper_commit_tail+0x2a/0x70 commit_tail+0xf1/0x150 drm_atomic_helper_commit+0x13c/0x180 drm_atomic_commit+0xb1/0xe0 info ? __pfx___drm_printfn_info+0x10/0x10 drm_mode_atomic_ioctl+0x70f/0x7c0 ? __pfx_drm_mode_atomic_ioctl+0x10/0x10 drm_ioctl_kernel+0xae/0x100 drm_ioctl+0x2a8/0x550 ? __pfx_drm_mode_atomic_ioctl+0x10/0x10 __x64_sys_ioctl+0x97/0xe0 do_syscall_64+0x7e/0x7f0 ? __ct_user_enter+0x56/0xd0 ? do_syscall_64+0x158/0x7f0 ? __ct_user_enter+0x56/0xd0 ? do_syscall_64+0x158/0x7f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Split out crtc handling from gud_plane_atomic_update() into atomic_enable() and atomic_disable() functions to delegate crtc state transitioning work to the DRM helpers. To preserve the gud state commit sequence [2], switch to the runtime PM version of drm_atomic_helper_commit_tail() which ensures that crtcs are enabled (hence sending the GUD_REQ_SET_CONTROLLER_ENABLE and GUD_REQ_SET_DISPLAY_ENABLE requests) before a framebuffer update is sent. [1] https://lore.kernel.org/all/20251231055039.44266-1-me@shenghaoyang.info/ [2] https://github.com/notro/gud/wiki/GUD-Protocol#display-state Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/202601142159.0v8ilfVs-lkp@intel.com/ Fixes: 73cfd166e045 ("drm/gud: Replace simple display pipe with DRM atomic helpers") Signed-off-by: Shenghao Yang --- v5: Send SET_CONTROLLER_ENABLE and SET_STATE_COMMIT unconditionally on crtc enable v4: Send SET_DISPLAY_ENABLE=1 unconditionally on crtc enable v3: Dropped stable AUTOSEL opt out v2: Moved controller and display control commands to crtc enable / disable functions. [v4]: https://lore.kernel.org/lkml/20260218054711.63982-1-me@shenghaoyang.info/ [v3]: https://lore.kernel.org/lkml/20260203172630.10077-1-me@shenghaoyang.info/ [v2]: https://lore.kernel.org/lkml/20260201095956.21042-1-me@shenghaoyang.info/ [v1]: https://lore.kernel.org/lkml/20260118125044.54467-1-me@shenghaoyang.info/ drivers/gpu/drm/gud/gud_drv.c | 9 ++++- drivers/gpu/drm/gud/gud_internal.h | 4 +++ drivers/gpu/drm/gud/gud_pipe.c | 54 ++++++++++++++++++++---------- 3 files changed, 48 insertions(+), 19 deletions(-) diff --git a/drivers/gpu/drm/gud/gud_drv.c b/drivers/gpu/drm/gud/gud_drv.c index d0122d477610..17c2dead2c13 100644 --- a/drivers/gpu/drm/gud/gud_drv.c +++ b/drivers/gpu/drm/gud/gud_drv.c @@ -339,7 +339,9 @@ static int gud_stats_debugfs(struct seq_file *m, void *data) } static const struct drm_crtc_helper_funcs gud_crtc_helper_funcs = { - .atomic_check = drm_crtc_helper_atomic_check + .atomic_check = drm_crtc_helper_atomic_check, + .atomic_enable = gud_crtc_atomic_enable, + .atomic_disable = gud_crtc_atomic_disable, }; static const struct drm_crtc_funcs gud_crtc_funcs = { @@ -364,6 +366,10 @@ static const struct drm_plane_funcs gud_plane_funcs = { DRM_GEM_SHADOW_PLANE_FUNCS, }; +static const struct drm_mode_config_helper_funcs gud_mode_config_helpers = { + .atomic_commit_tail = drm_atomic_helper_commit_tail_rpm, +}; + static const struct drm_mode_config_funcs gud_mode_config_funcs = { .fb_create = drm_gem_fb_create_with_dirty, .atomic_check = drm_atomic_helper_check, @@ -499,6 +505,7 @@ static int gud_probe(struct usb_interface *intf, const struct usb_device_id *id) drm->mode_config.min_height = le32_to_cpu(desc.min_height); drm->mode_config.max_height = le32_to_cpu(desc.max_height); drm->mode_config.funcs = &gud_mode_config_funcs; + drm->mode_config.helper_private = &gud_mode_config_helpers; /* Format init */ formats_dev = devm_kmalloc(dev, GUD_FORMATS_MAX_NUM, GFP_KERNEL); diff --git a/drivers/gpu/drm/gud/gud_internal.h b/drivers/gpu/drm/gud/gud_internal.h index d27c31648341..a5b7e53cf79c 100644 --- a/drivers/gpu/drm/gud/gud_internal.h +++ b/drivers/gpu/drm/gud/gud_internal.h @@ -62,6 +62,10 @@ int gud_usb_set_u8(struct gud_device *gdrm, u8 request, u8 val); void gud_clear_damage(struct gud_device *gdrm); void gud_flush_work(struct work_struct *work); +void gud_crtc_atomic_enable(struct drm_crtc *crtc, + struct drm_atomic_state *state); +void gud_crtc_atomic_disable(struct drm_crtc *crtc, + struct drm_atomic_state *state); int gud_plane_atomic_check(struct drm_plane *plane, struct drm_atomic_state *state); void gud_plane_atomic_update(struct drm_plane *plane, diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c index 4b77be94348d..587d6dd2b32e 100644 --- a/drivers/gpu/drm/gud/gud_pipe.c +++ b/drivers/gpu/drm/gud/gud_pipe.c @@ -580,6 +580,39 @@ int gud_plane_atomic_check(struct drm_plane *plane, return ret; } +void gud_crtc_atomic_enable(struct drm_crtc *crtc, + struct drm_atomic_state *state) +{ + struct drm_device *drm = crtc->dev; + struct gud_device *gdrm = to_gud_device(drm); + int idx; + + if (!drm_dev_enter(drm, &idx)) + return; + + gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 1); + gud_usb_set(gdrm, GUD_REQ_SET_STATE_COMMIT, 0, NULL, 0); + gud_usb_set_u8(gdrm, GUD_REQ_SET_DISPLAY_ENABLE, 1); + + drm_dev_exit(idx); +} + +void gud_crtc_atomic_disable(struct drm_crtc *crtc, + struct drm_atomic_state *state) +{ + struct drm_device *drm = crtc->dev; + struct gud_device *gdrm = to_gud_device(drm); + int idx; + + if (!drm_dev_enter(drm, &idx)) + return; + + gud_usb_set_u8(gdrm, GUD_REQ_SET_DISPLAY_ENABLE, 0); + gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 0); + + drm_dev_exit(idx); +} + void gud_plane_atomic_update(struct drm_plane *plane, struct drm_atomic_state *atomic_state) { @@ -607,24 +640,12 @@ void gud_plane_atomic_update(struct drm_plane *plane, mutex_unlock(&gdrm->damage_lock); } - if (!drm_dev_enter(drm, &idx)) + if (!crtc || !drm_dev_enter(drm, &idx)) return; - if (!old_state->fb) - gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 1); - - if (fb && (crtc->state->mode_changed || crtc->state->connectors_changed)) - gud_usb_set(gdrm, GUD_REQ_SET_STATE_COMMIT, 0, NULL, 0); - - if (crtc->state->active_changed) - gud_usb_set_u8(gdrm, GUD_REQ_SET_DISPLAY_ENABLE, crtc->state->active); - - if (!fb) - goto ctrl_disable; - ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE); if (ret) - goto ctrl_disable; + goto out; drm_atomic_helper_damage_iter_init(&iter, old_state, new_state); drm_atomic_for_each_plane_damage(&iter, &damage) @@ -632,9 +653,6 @@ void gud_plane_atomic_update(struct drm_plane *plane, drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE); -ctrl_disable: - if (!crtc->state->enable) - gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 0); - +out: drm_dev_exit(idx); } -- 2.53.0