From 933db73351d359f74b14f4af095808260aff11f9 Mon Sep 17 00:00:00 2001

From: Vasily Averin vvs@virtuozzo.com Date: Wed, 29 Apr 2020 12:01:24 +0300 Subject: [PATCH] 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.

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-8d32419... Signed-off-by: Gerd Hoffmann kraxel@redhat.com

backported to v4.9-stable

Signed-off-by: Vasily Averin vvs@virtuozzo.com --- drivers/gpu/drm/qxl/qxl_cmd.c | 5 ++--- drivers/gpu/drm/qxl/qxl_display.c | 8 ++++---- drivers/gpu/drm/qxl/qxl_draw.c | 8 ++++---- drivers/gpu/drm/qxl/qxl_ioctl.c | 5 +---- 4 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_cmd.c b/drivers/gpu/drm/qxl/qxl_cmd.c index 04270f5d110c..91774756ae99 100644 --- a/drivers/gpu/drm/qxl/qxl_cmd.c +++ b/drivers/gpu/drm/qxl/qxl_cmd.c @@ -528,8 +528,8 @@ 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); @@ -571,9 +571,8 @@ 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 a61c0d460ec2..f8a1f84c8838 100644 --- 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 9b728edf1b49..f32b663e5bbc 100644 --- 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) @@ -381,8 +381,8 @@ 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) @@ -432,8 +432,8 @@ 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) @@ -476,8 +476,8 @@ 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 5a4c8c492683..db0afb0613c9 100644 --- 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: