>From 933db73351d359f74b14f4af095808260aff11f9 Mon Sep 17 00:00:00 2001
From: Vasily Averin <vvs@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Fixes: f64122c1f6ad ("drm: add new QXL driver. (v1.4)")
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/fa17b338-66ae-f299-68fe-8d32419d9071@xxxxxxxxxxxxx
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
backported to v4.4-stable
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
---
drivers/gpu/drm/qxl/qxl_cmd.c | 5 ++---
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(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/qxl/qxl_cmd.c b/drivers/gpu/drm/qxl/qxl_cmd.c
index fdc1833b1af8..45e08a685102 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 5edebf495c07..0d6cc396cc16 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;
}
@@ -390,8 +390,8 @@ 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);
@@ -450,8 +450,8 @@ 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 c8ccb3765597..47da124b7ebf 100644
--- a/drivers/gpu/drm/qxl/qxl_draw.c
+++ b/drivers/gpu/drm/qxl/qxl_draw.c
@@ -245,8 +245,8 @@ 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)
@@ -386,8 +386,8 @@ 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)
@@ -437,8 +437,8 @@ 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)
@@ -481,8 +481,8 @@ 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 7c2e78201ead..4d852449a7d1 100644
--- 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:
--
2.17.1
