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drm/vmwgfx: Fix possible usage of an uninitialized variable

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vmw_user_bo_lookup can fail to lookup user buffers, especially because
the buffer handles come from the userspace. The return value has
to be checked before the buffers are put back.

This was spotted by Dan's Smatch statick checker:
    drivers/gpu/drm/vmwgfx/vmwgfx_bo.c:574 vmw_user_bo_synccpu_release()
	error: uninitialized symbol 'vmw_bo'.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 8afa13a0583f ("drm/vmwgfx: Implement DRIVER_GEM")
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211215200224.3693345-1-zack@kde.org
(cherry picked from commit 60c9ecd705be3a28f79d70ea21c3939db668bf46)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
This commit is contained in:
Zack Rusin 2021-12-15 15:02:24 -05:00 committed by Thomas Zimmermann
parent 50ca8cc7c0
commit 58fa0d90ed
1 changed files with 5 additions and 3 deletions
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8
drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
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@ -568,10 +568,12 @@ static int vmw_user_bo_synccpu_release(struct drm_file *filp,
struct vmw_buffer_object *vmw_bo;
int ret = vmw_user_bo_lookup(filp, handle, &vmw_bo);
if (!(flags & drm_vmw_synccpu_allow_cs)) {
atomic_dec(&vmw_bo->cpu_writers);
if (!ret) {
if (!(flags & drm_vmw_synccpu_allow_cs)) {
atomic_dec(&vmw_bo->cpu_writers);
}
ttm_bo_put(&vmw_bo->base);
}
ttm_bo_put(&vmw_bo->base);
return ret;
}