linux-hardening - [PATCH] dmaengine: stm32-dma3: Set lli

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Message-Id: <20240716213830.work.951-kees@kernel.org>
Date: Tue, 16 Jul 2024 14:38:33 -0700
From: Kees Cook <kees@...nel.org>
To: Amélie Delaunay <amelie.delaunay@...s.st.com>
Cc: Kees Cook <kees@...nel.org>,
	Vinod Koul <vkoul@...nel.org>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	dmaengine@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH] dmaengine: stm32-dma3: Set lli_size after allocation

With the new __counted_by annotation, the "lli_size" variable needs to
valid for accesses to the "lli" array. This requirement is not met in
stm32_dma3_chan_desc_alloc(), since "lli_size" starts at "0", so "lli"
index "0" will not be considered valid during the initialization for loop.

Fix this by setting lli_size immediately after allocation (similar to
how this is handled in stm32_mdma_alloc_desc() for the node/count
relationship).

Fixes: f561ec8b2b33 ("dmaengine: Add STM32 DMA3 support")
Signed-off-by: Kees Cook <kees@...nel.org>
---
Cc: "Amélie Delaunay" <amelie.delaunay@...s.st.com>
Cc: Vinod Koul <vkoul@...nel.org>
Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: dmaengine@...r.kernel.org
Cc: linux-stm32@...md-mailman.stormreply.com
Cc: linux-arm-kernel@...ts.infradead.org
---
 drivers/dma/stm32/stm32-dma3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c
index 4087e0263a48..0be6e944df6f 100644
--- a/drivers/dma/stm32/stm32-dma3.c
+++ b/drivers/dma/stm32/stm32-dma3.c
@@ -403,6 +403,7 @@ static struct stm32_dma3_swdesc *stm32_dma3_chan_desc_alloc(struct stm32_dma3_ch
 	swdesc = kzalloc(struct_size(swdesc, lli, count), GFP_NOWAIT);
 	if (!swdesc)
 		return NULL;
+	swdesc->lli_size = count;
 
 	for (i = 0; i < count; i++) {
 		swdesc->lli[i].hwdesc = dma_pool_zalloc(chan->lli_pool, GFP_NOWAIT,
@@ -410,7 +411,6 @@ static struct stm32_dma3_swdesc *stm32_dma3_chan_desc_alloc(struct stm32_dma3_ch
 		if (!swdesc->lli[i].hwdesc)
 			goto err_pool_free;
 	}
-	swdesc->lli_size = count;
 	swdesc->ccr = 0;
 
 	/* Set LL base address */
-- 
2.34.1