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* [PATCH] dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic
@ 2021-09-18 10:40 Len Baker
  2021-09-21  0:00 ` Gustavo A. R. Silva
  0 siblings, 1 reply; 3+ messages in thread
From: Len Baker @ 2021-09-18 10:40 UTC (permalink / raw)
  To: Daniel Mack, Haojian Zhuang, Robert Jarzmik, Vinod Koul
  Cc: Len Baker, Gustavo A. R. Silva, Kees Cook, linux-arm-kernel,
	dmaengine, linux-hardening, linux-kernel

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kzalloc() function.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/dma/pxa_dma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 4a2a796e348c..52d04641e361 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -742,8 +742,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc)
 	dma_addr_t dma;
 	int i;

-	sw_desc = kzalloc(sizeof(*sw_desc) +
-			  nb_hw_desc * sizeof(struct pxad_desc_hw *),
+	sw_desc = kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc),
 			  GFP_NOWAIT);
 	if (!sw_desc)
 		return NULL;
--
2.25.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-10-20 23:27 UTC | newest]

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2021-09-18 10:40 [PATCH] dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic Len Baker
2021-09-21  0:00 ` Gustavo A. R. Silva
2021-10-20 23:32   ` Gustavo A. R. Silva

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