linux-kernel - [PATCH 5.14 428/432] drm/ttm: Fix ttm_bo_move_memcpy() for subclassed struct ttm

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Message-Id: <20210916155825.348520145@linuxfoundation.org>
Date:   Thu, 16 Sep 2021 18:02:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ben Skeggs <skeggsb@...il.com>,
        Dave Airlie <airlied@...il.com>,
        Christian König <christian.koenig@....com>,
        Thomas Hellström 
        <thomas.hellstrom@...ux.intel.com>, Ben Skeggs <bskeggs@...hat.com>
Subject: [PATCH 5.14 428/432] drm/ttm: Fix ttm_bo_move_memcpy() for subclassed struct ttm_resource

From: Thomas Hellström <thomas.hellstrom@...ux.intel.com>

commit efcefc7127290e7e9fa98dea029163ad8eda8fb3 upstream.

The code was making a copy of a struct ttm_resource. However,
recently the struct ttm_resources were allowed to be subclassed and
also were allowed to be malloced, hence the driver could end up assuming
the copy we handed it was subclassed and worse, the original could have
been freed at this point.

Fix this by using the original struct ttm_resource before it is
potentially freed in ttm_bo_move_sync_cleanup()

v2: Base on drm-misc-next-fixes rather than drm-tip.

Reported-by: Ben Skeggs <skeggsb@...il.com>
Reported-by: Dave Airlie <airlied@...il.com>
Cc: Christian König <christian.koenig@....com>
Cc: <stable@...r.kernel.org>
Fixes: 3bf3710e3718 ("drm/ttm: Add a generic TTM memcpy move for page-based iomem")
Signed-off-by: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
Reviewed-by: Christian König <christian.koenig@....com>
Reviewed-by: Ben Skeggs <bskeggs@...hat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210831071536.80636-1-thomas.hellstrom@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/ttm/ttm_bo_util.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -143,7 +143,6 @@ int ttm_bo_move_memcpy(struct ttm_buffer
 	struct ttm_resource *src_mem = bo->resource;
 	struct ttm_resource_manager *src_man =
 		ttm_manager_type(bdev, src_mem->mem_type);
-	struct ttm_resource src_copy = *src_mem;
 	union {
 		struct ttm_kmap_iter_tt tt;
 		struct ttm_kmap_iter_linear_io io;
@@ -173,11 +172,11 @@ int ttm_bo_move_memcpy(struct ttm_buffer
 	}
 
 	ttm_move_memcpy(bo, dst_mem->num_pages, dst_iter, src_iter);
-	src_copy = *src_mem;
-	ttm_bo_move_sync_cleanup(bo, dst_mem);
 
 	if (!src_iter->ops->maps_tt)
-		ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, &src_copy);
+		ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, src_mem);
+	ttm_bo_move_sync_cleanup(bo, dst_mem);
+
 out_src_iter:
 	if (!dst_iter->ops->maps_tt)
 		ttm_kmap_iter_linear_io_fini(&_dst_iter.io, bdev, dst_mem);