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* [PATCH] net: mana: Prefer struct_size over open coded arithmetic
@ 2021-09-11 10:28 Len Baker
  2021-09-11 13:36 ` Haiyang Zhang
  2021-09-18 13:20 ` Len Baker
  0 siblings, 2 replies; 7+ messages in thread
From: Len Baker @ 2021-09-11 10:28 UTC (permalink / raw)
  To: K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger, Wei Liu,
	Dexuan Cui, David S. Miller, Jakub Kicinski, Sumit Semwal,
	Christian König, Kees Cook
  Cc: Len Baker, Colin Ian King, linux-hardening, linux-hyperv, netdev,
	linux-kernel, linux-media, dri-devel, linaro-mm-sig

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/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/net/ethernet/microsoft/mana/hw_channel.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/hw_channel.c b/drivers/net/ethernet/microsoft/mana/hw_channel.c
index 1a923fd99990..0efdc6c3c32a 100644
--- a/drivers/net/ethernet/microsoft/mana/hw_channel.c
+++ b/drivers/net/ethernet/microsoft/mana/hw_channel.c
@@ -398,9 +398,7 @@ static int mana_hwc_alloc_dma_buf(struct hw_channel_context *hwc, u16 q_depth,
 	int err;
 	u16 i;

-	dma_buf = kzalloc(sizeof(*dma_buf) +
-			  q_depth * sizeof(struct hwc_work_request),
-			  GFP_KERNEL);
+	dma_buf = kzalloc(struct_size(dma_buf, reqs, q_depth), GFP_KERNEL);
 	if (!dma_buf)
 		return -ENOMEM;

--
2.25.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-09-19  8:27 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2021-09-11 10:28 [PATCH] net: mana: Prefer struct_size over open coded arithmetic Len Baker
2021-09-11 13:36 ` Haiyang Zhang
2021-09-18 13:20 ` Len Baker
2021-09-18 13:51   ` Kees Cook
2021-09-18 17:11     ` Len Baker
2021-09-18 17:06   ` Dexuan Cui
2021-09-19  8:27     ` Len Baker

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