android-mainline/ANDROID-virtio-disable-virtio_dma_buf-callback-checks-with-CFI.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sami Tolvanen <samitolvanen@google.com>
Date: Thu, 28 Jan 2021 11:35:05 -0800
Subject: ANDROID: virtio: disable virtio_dma_buf callback checks with CFI

CONFIG_CFI_CLANG breaks cross-module function address equality, which
breaks virtio_dma_buf as it compares a locally taken function address to
a one passed from a different module. Remove these sanity checks for now
to allow Cuttlefish to boot with CFI.

Bug: 178495907
Bug: 199547335
Change-Id: I508e2fa9e3ddd888dc2fdb743cec20a400eaf1f5
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Alistair Delva <adelva@google.com>
Signed-off-by: Lee Jones <joneslee@google.com>
---
 drivers/virtio/virtio_dma_buf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_dma_buf.c b/drivers/virtio/virtio_dma_buf.c
--- a/drivers/virtio/virtio_dma_buf.c
+++ b/drivers/virtio/virtio_dma_buf.c
@@ -25,11 +25,14 @@ struct dma_buf *virtio_dma_buf_export
 			     const struct virtio_dma_buf_ops, ops);
 
 	if (!exp_info->ops ||
-	    exp_info->ops->attach != &virtio_dma_buf_attach ||
 	    !virtio_ops->get_uuid) {
 		return ERR_PTR(-EINVAL);
 	}
 
+	if (!(IS_ENABLED(CONFIG_CFI_CLANG) && IS_ENABLED(CONFIG_MODULES)) &&
+	    exp_info->ops->attach != &virtio_dma_buf_attach)
+		return ERR_PTR(-EINVAL);
+
 	return dma_buf_export(exp_info);
 }
 EXPORT_SYMBOL(virtio_dma_buf_export);
@@ -60,6 +63,9 @@ EXPORT_SYMBOL(virtio_dma_buf_attach);
  */
 bool is_virtio_dma_buf(struct dma_buf *dma_buf)
 {
+	if (IS_ENABLED(CONFIG_CFI_CLANG) && IS_ENABLED(CONFIG_MODULES))
+		return true;
+
 	return dma_buf->ops->attach == &virtio_dma_buf_attach;
 }
 EXPORT_SYMBOL(is_virtio_dma_buf);