drm/qxl: qxl_release use after free

commit 933db73351d359f74b14f4af095808260aff11f9 upstream.

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.

It can lead to crashes in qxl driver or trigger memory corruption
in some kmalloc-192 slab object

Gerd Hoffmann proposes to swap the qxl_release_fence_buffer_objects() +
qxl_push_{cursor,command}_ring_release() calls to close that race window.

cc: stable@vger.kernel.org
Fixes: f64122c1f6ad ("drm: add new QXL driver. (v1.4)")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Link: http://patchwork.freedesktop.org/patch/msgid/fa17b338-66ae-f299-68fe-8d32419d9071@virtuozzo.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
[backported to v.4.19 stable]
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/qxl/qxl_cmd.c b/drivers/gpu/drm/qxl/qxl_cmd.c
index a043591a0aa160907941b9cc19f546afaff06ee6..5177e37d81e65fdb9377386397b0b4ea09fe9698 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_cmd.c
+++ b/drivers/gpu/drm/qxl/qxl_cmd.c
@@ -501,8 +501,8 @@ 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);
@@ -544,9 +544,8 @@ 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 0570c6826bff40911b120cb1a99e56a3db5ac421..769e12b4c13c58be10572003930ad0459da771df 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -532,8 +532,8 @@ 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;
 
@@ -694,8 +694,8 @@ 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)
                qxl_bo_unref(&old_cursor_bo);
@@ -740,8 +740,8 @@ 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 67f3bdeaa3bfad1a79460f32d78111f0c26e78f4..d009f2bc28e93d2efd4a77770b623ab99cf58d82 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_draw.c
+++ b/drivers/gpu/drm/qxl/qxl_draw.c
@@ -241,8 +241,8 @@ 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:
        if (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 6cc9f3367fa05581a90280b7cc111259cc2692fa..5536b2f7b7b00c9b31d0ff46b6f9506e30d9ec05 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_ioctl.c
+++ b/drivers/gpu/drm/qxl/qxl_ioctl.c
@@ -257,11 +257,8 @@ 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: