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 v4.9-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 4df9c5a8ec639536304255cbb0dcbc687edced2c..3e6fd393da15472a5169422b1cbe5127c66aaf7d 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_cmd.c
+++ b/drivers/gpu/drm/qxl/qxl_cmd.c
@@ -529,8 +529,8 @@ 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);
@@ -572,9 +572,8 @@ 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 a61c0d460ec2dd018463389d63c243b532ad55db..f8a1f84c8838df04f1fe582c8a42c77be653c0c0 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -292,8 +292,8 @@ qxl_hide_cursor(struct qxl_device *qdev)
        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);
        return 0;
 }
 
@@ -333,8 +333,8 @@ static int qxl_crtc_apply_cursor(struct drm_crtc *crtc)
        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;
 
@@ -436,8 +436,8 @@ static int qxl_crtc_cursor_set2(struct drm_crtc *crtc,
        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);
 
        /* finish with the userspace bo */
        ret = qxl_bo_reserve(user_bo, false);
@@ -497,8 +497,8 @@ static int qxl_crtc_cursor_move(struct drm_crtc *crtc,
        cmd->u.position.y = qcrtc->cur_y + qcrtc->hot_spot_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);
 
        return 0;
 }

diff --git a/drivers/gpu/drm/qxl/qxl_draw.c b/drivers/gpu/drm/qxl/qxl_draw.c
index 28cc606880543f8826c614a5ffeeb4b87ea5dc5a..d1407d162877048dd8143ecb87d0858fe67c1327 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 5a4c8c492683048156b853b7a88fce4582b51b90..db0afb0613c93df4390c1577342d6e799fb59809 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_ioctl.c
+++ b/drivers/gpu/drm/qxl/qxl_ioctl.c
@@ -256,11 +256,8 @@ 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: