linux-kernel - [PATCH] media: videobuf2: Explicitly state max size of planes

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Message-Id: <20210310104639.1069974-1-ribalda@chromium.org>
Date:   Wed, 10 Mar 2021 11:46:39 +0100
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Tomasz Figa <tfiga@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH] media: videobuf2: Explicitly state max size of planes

The plane size needs to be PAGE_ALIGNED, so it is not possible to have
sizes bigger than MAX_INT - PAGE_SIZE.

We already check for overflows when that happen:
 if (size < vb->planes[plane].length)
	goto free;

But it is good to explicitly state our max allowed value, in order to
align with the driver expectations.

Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 include/media/videobuf2-core.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 799ba61b5b6f..12955cb460d2 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -154,9 +154,11 @@ struct vb2_mem_ops {
  * @dbuf:	dma_buf - shared buffer object.
  * @dbuf_mapped:	flag to show whether dbuf is mapped or not
  * @bytesused:	number of bytes occupied by data in the plane (payload).
- * @length:	size of this plane (NOT the payload) in bytes.
+ * @length:	size of this plane (NOT the payload) in bytes. The maximum
+ *		valid size is MAX_UINT - PAGE_SIZE.
  * @min_length:	minimum required size of this plane (NOT the payload) in bytes.
- *		@length is always greater or equal to @min_length.
+ *		@length is always greater or equal to @min_length, and like
+ *		@length, it is limited to MAX_UINT - PAGE_SIZE.
  * @m:		Union with memtype-specific data.
  * @m.offset:	when memory in the associated struct vb2_buffer is
  *		%VB2_MEMORY_MMAP, equals the offset from the start of
-- 
2.30.1.766.gb4fecdf3b7-goog