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@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Karol Herbst <karolherbst@xxxxxxxxx>
> ---
> 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
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
