From e09bd07d8f5a83bb9b2620b110a88dc8a7ecf7da Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Mon, 24 Jul 2023 13:26:10 +0200
Subject: [PATCH] drm/shmem-helper: Reset vma->vm_ops before calling
dma_buf_mmap()
commit 07dd476f6116966cb2006e25fdcf48f0715115ff upstream.
The dma-buf backend is supposed to provide its own vm_ops, but some
implementation just have nothing special to do and leave vm_ops
untouched, probably expecting this field to be zero initialized (this
is the case with the system_heap implementation for instance).
Let's reset vma->vm_ops to NULL to keep things working with these
implementations.
Fixes: 26d3ac3cb04d ("drm/shmem-helpers: Redirect mmap for imported dma-buf")
Cc: <stable@vger.kernel.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reported-by: Roman Stratiienko <r.stratiienko@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Roman Stratiienko <r.stratiienko@gmail.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230724112610.60974-1-boris.brezillon@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index b7bb5610dfe21..e8f07305e279a 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -614,7 +614,13 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
int ret;
if (obj->import_attach) {
+ /* Reset both vm_ops and vm_private_data, so we don't end up with
+ * vm_ops pointing to our implementation if the dma-buf backend
+ * doesn't set those fields.
+ */
vma->vm_private_data = NULL;
+ vma->vm_ops = NULL;
+
ret = dma_buf_mmap(obj->dma_buf, vma, 0);
/* Drop the reference drm_gem_mmap_obj() acquired.*/
--
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