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drm/vmwgfx: drop dma_buf reference on foreign-fd prime import

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ttm_prime_fd_to_handle() returns -ENOSYS when the imported fd's
dma_buf->ops do not match the ttm_object_device's ops, but does so
without releasing the reference acquired by dma_buf_get().  Any
unprivileged renderD client passing a non-vmwgfx prime fd through the
DRM_VMW_GB_SURFACE_REF{,_EXT} path leaks one dma_buf reference per
call and indefinitely pins the foreign exporter's GEM resources.

Funnel the error path through the existing dma_buf_put() so the
reference is always dropped.

Fixes: 65981f7681 ("drm/ttm: Add a minimal prime implementation for ttm base objects")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4.7
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Reviewed-by: Ian Forbes <ian.forbes@broadcom.com>
Link: https://patch.msgid.link/20260505222728.519626-6-zack.rusin@broadcom.com
This commit is contained in:
Zack Rusin
2026-07-27 11:29:24 -04:00
parent 250af2e8c3
commit f739416dc5
1 changed files with 5 additions and 2 deletions
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drivers/gpu/drm/vmwgfx/ttm_object.c
+5 -2
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@@ -547,14 +547,17 @@ int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
if (IS_ERR(dma_buf))
return PTR_ERR(dma_buf);
if (dma_buf->ops != &tdev->ops)
return -ENOSYS;
if (dma_buf->ops != &tdev->ops) {
ret = -ENOSYS;
goto out;
}
prime = (struct ttm_prime_object *) dma_buf->priv;
base = &prime->base;
*handle = base->handle;
ret = ttm_ref_object_add(tfile, base, NULL, false);
out:
dma_buf_put(dma_buf);
return ret;