[Devel] [PATCH RHEL7 COMMIT] drm/qxl: qxl_release use after free
Konstantin Khorenko
khorenko at virtuozzo.com
Thu Apr 30 18:36:57 MSK 2020
The commit is pushed to "branch-rh7-3.10.0-1127.vz7.150.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1127.vz7.150.5
------>
commit 7d8b7a2f375d0023796a2908ed1d28b6ac848b3d
Author: Vasily Averin <vvs at virtuozzo.com>
Date: Thu Apr 30 18:36:56 2020 +0300
drm/qxl: qxl_release use after free
qxl_release should not be accesses after qxl_push_*_ring_release() calls:
userspace driver can process submitted command quickly, move qxl_release
into release_ring, generate interrupt and trigger garbage collector.
Gerd Hoffmann proposes to swap the qxl_release_fence_buffer_objects() +
qxl_push_{cursor,command}_ring_release() calls to close that race window.
https://jira.sw.ru/browse/PSBM-102320
Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
---
drivers/gpu/drm/qxl/qxl_cmd.c | 6 ++----
drivers/gpu/drm/qxl/qxl_display.c | 6 +++---
drivers/gpu/drm/qxl/qxl_draw.c | 8 ++++----
drivers/gpu/drm/qxl/qxl_ioctl.c | 5 +----
4 files changed, 10 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/qxl/qxl_cmd.c b/drivers/gpu/drm/qxl/qxl_cmd.c
index 89cddf62b22e0..53b6863ca8a04 100644
--- a/drivers/gpu/drm/qxl/qxl_cmd.c
+++ b/drivers/gpu/drm/qxl/qxl_cmd.c
@@ -504,8 +504,8 @@ int qxl_hw_surface_alloc(struct qxl_device *qdev,
/* no need to add a release to the fence for this surface bo,
since it is only released when we ask to destroy the surface
and it would never signal otherwise */
- qxl_push_command_ring_release(qdev, release, QXL_CMD_SURFACE, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_command_ring_release(qdev, release, QXL_CMD_SURFACE, false);
surf->hw_surf_alloc = true;
spin_lock(&qdev->surf_id_idr_lock);
@@ -547,10 +547,8 @@ int qxl_hw_surface_dealloc(struct qxl_device *qdev,
cmd->surface_id = id;
qxl_release_unmap(qdev, release, &cmd->release_info);
- qxl_push_command_ring_release(qdev, release, QXL_CMD_SURFACE, false);
-
qxl_release_fence_buffer_objects(release);
-
+ qxl_push_command_ring_release(qdev, release, QXL_CMD_SURFACE, false);
return 0;
}
diff --git a/drivers/gpu/drm/qxl/qxl_display.c b/drivers/gpu/drm/qxl/qxl_display.c
index ce0b9c40fc212..e38cbe3283fbe 100644
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -511,8 +511,8 @@ static int qxl_primary_apply_cursor(struct drm_plane *plane)
cmd->u.set.visible = 1;
qxl_release_unmap(qdev, release, &cmd->release_info);
- qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
return ret;
@@ -671,8 +671,8 @@ static void qxl_cursor_atomic_update(struct drm_plane *plane,
cmd->u.position.y = plane->state->crtc_y + fb->hot_y;
qxl_release_unmap(qdev, release, &cmd->release_info);
- qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
if (old_cursor_bo != NULL)
qxl_bo_unpin(old_cursor_bo);
@@ -719,8 +719,8 @@ static void qxl_cursor_atomic_disable(struct drm_plane *plane,
cmd->type = QXL_CURSOR_HIDE;
qxl_release_unmap(qdev, release, &cmd->release_info);
- qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
}
static int qxl_plane_prepare_fb(struct drm_plane *plane,
diff --git a/drivers/gpu/drm/qxl/qxl_draw.c b/drivers/gpu/drm/qxl/qxl_draw.c
index 4a43b5ba4aa07..a6b8b68220ded 100644
--- a/drivers/gpu/drm/qxl/qxl_draw.c
+++ b/drivers/gpu/drm/qxl/qxl_draw.c
@@ -243,8 +243,8 @@ void qxl_draw_opaque_fb(const struct qxl_fb_image *qxl_fb_image,
qxl_bo_physical_address(qdev, dimage->bo, 0);
qxl_release_unmap(qdev, release, &drawable->release_info);
- qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
out_free_palette:
qxl_bo_unref(&palette_bo);
@@ -382,8 +382,8 @@ void qxl_draw_dirty_fb(struct qxl_device *qdev,
}
qxl_bo_kunmap(clips_bo);
- qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
out_release_backoff:
if (ret)
@@ -433,8 +433,8 @@ void qxl_draw_copyarea(struct qxl_device *qdev,
drawable->u.copy_bits.src_pos.y = sy;
qxl_release_unmap(qdev, release, &drawable->release_info);
- qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
out_free_release:
if (ret)
@@ -477,8 +477,8 @@ void qxl_draw_fill(struct qxl_draw_fill *qxl_draw_fill_rec)
qxl_release_unmap(qdev, release, &drawable->release_info);
- qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
qxl_release_fence_buffer_objects(release);
+ qxl_push_command_ring_release(qdev, release, QXL_CMD_DRAW, false);
out_free_release:
if (ret)
diff --git a/drivers/gpu/drm/qxl/qxl_ioctl.c b/drivers/gpu/drm/qxl/qxl_ioctl.c
index 6e828158bcb02..d5d4c4105615d 100644
--- a/drivers/gpu/drm/qxl/qxl_ioctl.c
+++ b/drivers/gpu/drm/qxl/qxl_ioctl.c
@@ -259,11 +259,8 @@ static int qxl_process_single_command(struct qxl_device *qdev,
apply_surf_reloc(qdev, &reloc_info[i]);
}
+ qxl_release_fence_buffer_objects(release);
ret = qxl_push_command_ring_release(qdev, release, cmd->type, true);
- if (ret)
- qxl_release_backoff_reserve_list(release);
- else
- qxl_release_fence_buffer_objects(release);
out_free_bos:
out_free_release:
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