Message-ID: <20180713164552.GF3008@phenom.ffwll.local>
Date:   Fri, 13 Jul 2018 18:45:52 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Lyude Paul <lyude@...hat.com>
Cc:     nouveau@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        stable@...r.kernel.org, Ben Skeggs <bskeggs@...hat.com>
Subject: Re: [Nouveau] [PATCH 2/2] drm/nouveau: Avoid looping through fake
 MST connectors

On Fri, Jul 13, 2018 at 12:24:41PM -0400, Lyude Paul wrote:
> When MST and atomic were introduced to nouveau, another structure that
> could contain a drm_connector embedded within it was introduced; struct
> nv50_mstc. This meant that we no longer would be able to simply loop
> through our connector list and assume that nouveau_connector() would
> return a proper pointer for each connector, since the assertion that
> all connectors coming from nouveau have a full nouveau_connector struct
> became invalid.
> 
> Unfortunately, none of the actual code that looped through connectors
> ever got updated, which means that we've been causing invalid memory
> accesses for quite a while now.
> 
> An example that was caught by KASAN:
> 
> [  201.038698] ==================================================================
> [  201.038792] BUG: KASAN: slab-out-of-bounds in nvif_notify_get+0x190/0x1a0 [nouveau]
> [  201.038797] Read of size 4 at addr ffff88076738c650 by task kworker/0:3/718
> [  201.038800]
> [  201.038822] CPU: 0 PID: 718 Comm: kworker/0:3 Tainted: G           O      4.18.0-rc4Lyude-Test+ #1
> [  201.038825] Hardware name: LENOVO 20EQS64N0B/20EQS64N0B, BIOS N1EET78W (1.51 ) 05/18/2018
> [  201.038882] Workqueue: events nouveau_display_hpd_work [nouveau]
> [  201.038887] Call Trace:
> [  201.038894]  dump_stack+0xa4/0xfd
> [  201.038900]  print_address_description+0x71/0x239
> [  201.038929]  ? nvif_notify_get+0x190/0x1a0 [nouveau]
> [  201.038935]  kasan_report.cold.6+0x242/0x2fe
> [  201.038942]  __asan_report_load4_noabort+0x19/0x20
> [  201.038970]  nvif_notify_get+0x190/0x1a0 [nouveau]
> [  201.038998]  ? nvif_notify_put+0x1f0/0x1f0 [nouveau]
> [  201.039003]  ? kmsg_dump_rewind_nolock+0xe4/0xe4
> [  201.039049]  nouveau_display_init.cold.12+0x34/0x39 [nouveau]
> [  201.039089]  ? nouveau_user_framebuffer_create+0x120/0x120 [nouveau]
> [  201.039133]  nouveau_display_resume+0x5c0/0x810 [nouveau]
> [  201.039173]  ? nvkm_client_ioctl+0x20/0x20 [nouveau]
> [  201.039215]  nouveau_do_resume+0x19f/0x570 [nouveau]
> [  201.039256]  nouveau_pmops_runtime_resume+0xd8/0x2a0 [nouveau]
> [  201.039264]  pci_pm_runtime_resume+0x130/0x250
> [  201.039269]  ? pci_restore_standard_config+0x70/0x70
> [  201.039275]  __rpm_callback+0x1f2/0x5d0
> [  201.039279]  ? rpm_resume+0x560/0x18a0
> [  201.039283]  ? pci_restore_standard_config+0x70/0x70
> [  201.039287]  ? pci_restore_standard_config+0x70/0x70
> [  201.039291]  ? pci_restore_standard_config+0x70/0x70
> [  201.039296]  rpm_callback+0x175/0x210
> [  201.039300]  ? pci_restore_standard_config+0x70/0x70
> [  201.039305]  rpm_resume+0xcc3/0x18a0
> [  201.039312]  ? rpm_callback+0x210/0x210
> [  201.039317]  ? __pm_runtime_resume+0x9e/0x100
> [  201.039322]  ? kasan_check_write+0x14/0x20
> [  201.039326]  ? do_raw_spin_lock+0xc2/0x1c0
> [  201.039333]  __pm_runtime_resume+0xac/0x100
> [  201.039374]  nouveau_display_hpd_work+0x67/0x1f0 [nouveau]
> [  201.039380]  process_one_work+0x7a0/0x14d0
> [  201.039388]  ? cancel_delayed_work_sync+0x20/0x20
> [  201.039392]  ? lock_acquire+0x113/0x310
> [  201.039398]  ? kasan_check_write+0x14/0x20
> [  201.039402]  ? do_raw_spin_lock+0xc2/0x1c0
> [  201.039409]  worker_thread+0x86/0xb50
> [  201.039418]  kthread+0x2e9/0x3a0
> [  201.039422]  ? process_one_work+0x14d0/0x14d0
> [  201.039426]  ? kthread_create_worker_on_cpu+0xc0/0xc0
> [  201.039431]  ret_from_fork+0x3a/0x50
> [  201.039441]
> [  201.039444] Allocated by task 79:
> [  201.039449]  save_stack+0x43/0xd0
> [  201.039452]  kasan_kmalloc+0xc4/0xe0
> [  201.039456]  kmem_cache_alloc_trace+0x10a/0x260
> [  201.039494]  nv50_mstm_add_connector+0x9a/0x340 [nouveau]
> [  201.039504]  drm_dp_add_port+0xff5/0x1fc0 [drm_kms_helper]
> [  201.039511]  drm_dp_send_link_address+0x4a7/0x740 [drm_kms_helper]
> [  201.039518]  drm_dp_check_and_send_link_address+0x1a7/0x210 [drm_kms_helper]
> [  201.039525]  drm_dp_mst_link_probe_work+0x71/0xb0 [drm_kms_helper]
> [  201.039529]  process_one_work+0x7a0/0x14d0
> [  201.039533]  worker_thread+0x86/0xb50
> [  201.039537]  kthread+0x2e9/0x3a0
> [  201.039541]  ret_from_fork+0x3a/0x50
> [  201.039543]
> [  201.039546] Freed by task 0:
> [  201.039549] (stack is not available)
> [  201.039551]
> [  201.039555] The buggy address belongs to the object at ffff88076738c1a8
>                                  which belongs to the cache kmalloc-2048 of size 2048
> [  201.039559] The buggy address is located 1192 bytes inside of
>                                  2048-byte region [ffff88076738c1a8, ffff88076738c9a8)
> [  201.039563] The buggy address belongs to the page:
> [  201.039567] page:ffffea001d9ce200 count:1 mapcount:0 mapping:ffff88084000d0c0 index:0x0 compound_mapcount: 0
> [  201.039573] flags: 0x8000000000008100(slab|head)
> [  201.039578] raw: 8000000000008100 ffffea001da3be08 ffffea001da25a08 ffff88084000d0c0
> [  201.039582] raw: 0000000000000000 00000000000d000d 00000001ffffffff 0000000000000000
> [  201.039585] page dumped because: kasan: bad access detected
> [  201.039588]
> [  201.039591] Memory state around the buggy address:
> [  201.039594]  ffff88076738c500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [  201.039598]  ffff88076738c580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [  201.039601] >ffff88076738c600: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
> [  201.039604]                                                  ^
> [  201.039607]  ffff88076738c680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [  201.039611]  ffff88076738c700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [  201.039613] ==================================================================
> 
> Signed-off-by: Lyude Paul <lyude@...hat.com>
> Cc: stable@...r.kernel.org
> Cc: Karol Herbst <karolherbst@...il.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_connector.c |  2 +-
>  drivers/gpu/drm/nouveau/nouveau_connector.h | 24 ++++++++++++++++++++-
>  drivers/gpu/drm/nouveau/nouveau_display.c   |  4 ++--
>  3 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
> index 7dc380449232..af68eae4c626 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> @@ -1213,7 +1213,7 @@ nouveau_connector_create(struct drm_device *dev, int index)
>  	bool dummy;
>  
>  	drm_connector_list_iter_begin(dev, &conn_iter);
> -	drm_for_each_connector_iter(connector, &conn_iter) {
> +	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
>  		nv_connector = nouveau_connector(connector);
>  		if (nv_connector->index == index) {
>  			drm_connector_list_iter_end(&conn_iter);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.h b/drivers/gpu/drm/nouveau/nouveau_connector.h
> index a8cbb4b56fc7..aaf3a213c685 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.h
> @@ -33,6 +33,7 @@
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_dp_helper.h>
>  #include "nouveau_crtc.h"
> +#include "nouveau_encoder.h"
>  
>  struct nvkm_i2c_port;
>  
> @@ -60,6 +61,27 @@ static inline struct nouveau_connector *nouveau_connector(
>  	return container_of(con, struct nouveau_connector, base);
>  }
>  
> +static inline bool
> +nouveau_connector_is_mst(struct drm_connector *connector)
> +{
> +	const struct nouveau_encoder *nv_encoder;
> +	const struct drm_encoder *encoder;
> +
> +	if (connector->connector_type != DRM_MODE_CONNECTOR_DisplayPort)
> +		return false;
> +
> +	nv_encoder = find_encoder(connector, DCB_OUTPUT_ANY);
> +	if (!nv_encoder)
> +		return false;
> +
> +	encoder = &nv_encoder->base.base;
> +	return encoder->encoder_type == DRM_MODE_ENCODER_DPMST;
> +}
> +
> +#define nouveau_for_each_non_mst_connector_iter(connector, iter) \
> +	drm_for_each_connector_iter(connector, iter) \
> +		if (!nouveau_connector_is_mst(connector))

for_each_if() is more robust since it avoids the issues with dangling
else blocks.
-Daniel

> +
>  static inline struct nouveau_connector *
>  nouveau_crtc_connector_get(struct nouveau_crtc *nv_crtc)
>  {
> @@ -70,7 +92,7 @@ nouveau_crtc_connector_get(struct nouveau_crtc *nv_crtc)
>  	struct drm_crtc *crtc = to_drm_crtc(nv_crtc);
>  
>  	drm_connector_list_iter_begin(dev, &conn_iter);
> -	drm_for_each_connector_iter(connector, &conn_iter) {
> +	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
>  		if (connector->encoder && connector->encoder->crtc == crtc) {
>  			nv_connector = nouveau_connector(connector);
>  			break;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
> index 46b8430ef4aa..ec7861457b84 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_display.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_display.c
> @@ -413,7 +413,7 @@ nouveau_display_init(struct drm_device *dev)
>  
>  	/* enable hotplug interrupts */
>  	drm_connector_list_iter_begin(dev, &conn_iter);
> -	drm_for_each_connector_iter(connector, &conn_iter) {
> +	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
>  		struct nouveau_connector *conn = nouveau_connector(connector);
>  		nvif_notify_get(&conn->hpd);
>  	}
> @@ -444,7 +444,7 @@ nouveau_display_fini(struct drm_device *dev, bool suspend)
>  
>  	/* disable hotplug interrupts */
>  	drm_connector_list_iter_begin(dev, &conn_iter);
> -	drm_for_each_connector_iter(connector, &conn_iter) {
> +	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
>  		struct nouveau_connector *conn = nouveau_connector(connector);
>  		nvif_notify_put(&conn->hpd);
>  	}
> -- 
> 2.17.1
> 
> _______________________________________________
> Nouveau mailing list
> Nouveau@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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