linux-kernel - [PATCH 19/21] dmaengine: uniphier-xdmac: Annotate struct uniphier_xdmac_desc with __counted

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Message-Id: <20230817235859.49846-19-keescook@chromium.org>
Date:   Thu, 17 Aug 2023 16:58:56 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Hector Martin <marcan@...can.st>,
        Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Tudor Ambarus <tudor.ambarus@...aro.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Zhou Wang <wangzhou1@...ilicon.com>,
        Jie Hai <haijie1@...wei.com>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Green Wan <green.wan@...ive.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Peter Ujfalusi <peter.ujfalusi@...il.com>,
        Yu Kuai <yukuai3@...wei.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jordy Zomer <jordy@...ing.systems>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
        asahi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-tegra@...r.kernel.org, llvm@...ts.linux.dev,
        linux-hardening@...r.kernel.org
Subject: [PATCH 19/21] dmaengine: uniphier-xdmac: Annotate struct uniphier_xdmac_desc with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct uniphier_xdmac_desc.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Vinod Koul <vkoul@...nel.org>
Cc: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: dmaengine@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/dma/uniphier-xdmac.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/uniphier-xdmac.c b/drivers/dma/uniphier-xdmac.c
index 290836b7e1be..dd51522879a7 100644
--- a/drivers/dma/uniphier-xdmac.c
+++ b/drivers/dma/uniphier-xdmac.c
@@ -80,7 +80,7 @@ struct uniphier_xdmac_desc {
 	unsigned int nr_node;
 	unsigned int cur_node;
 	enum dma_transfer_direction dir;
-	struct uniphier_xdmac_desc_node nodes[];
+	struct uniphier_xdmac_desc_node nodes[] __counted_by(nr_node);
 };
 
 struct uniphier_xdmac_chan {
@@ -295,6 +295,7 @@ uniphier_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dst,
 	xd = kzalloc(struct_size(xd, nodes, nr), GFP_NOWAIT);
 	if (!xd)
 		return NULL;
+	xd->nr_node = nr;
 
 	for (i = 0; i < nr; i++) {
 		burst_size = min_t(size_t, len, XDMAC_MAX_WORD_SIZE);
@@ -309,7 +310,6 @@ uniphier_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dst,
 	}
 
 	xd->dir = DMA_MEM_TO_MEM;
-	xd->nr_node = nr;
 	xd->cur_node = 0;
 
 	return vchan_tx_prep(vc, &xd->vd, flags);
@@ -351,6 +351,7 @@ uniphier_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	xd = kzalloc(struct_size(xd, nodes, sg_len), GFP_NOWAIT);
 	if (!xd)
 		return NULL;
+	xd->nr_node = sg_len;
 
 	for_each_sg(sgl, sg, sg_len, i) {
 		xd->nodes[i].src = (direction == DMA_DEV_TO_MEM)
@@ -385,7 +386,6 @@ uniphier_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	}
 
 	xd->dir = direction;
-	xd->nr_node = sg_len;
 	xd->cur_node = 0;
 
 	return vchan_tx_prep(vc, &xd->vd, flags);
-- 
2.34.1