linux-hardening - [PATCH v2] dmaengine: pl08x: Use kcalloc() instead of kzalloc()

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Date: Sat, 30 Mar 2024 16:23:23 +0100
From: Erick Archer <erick.archer@...look.com>
To: Vinod Koul <vkoul@...nel.org>,
	Kees Cook <keescook@...omium.org>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Erick Archer <erick.archer@...look.com>,
	dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH v2] dmaengine: pl08x: Use kcalloc() instead of kzalloc()

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1].

Here the multiplication is obviously safe because the "channels"
member can only be 8 or 2. This value is set when the "vendor_data"
structs are initialized.

static struct vendor_data vendor_pl080 = {
	[...]
	.channels = 8,
	[...]
};

static struct vendor_data vendor_nomadik = {
	[...]
	.channels = 8,
	[...]
};

static struct vendor_data vendor_pl080s = {
	[...]
	.channels = 8,
	[...]
};

static struct vendor_data vendor_pl081 = {
	[...]
	.channels = 2,
	[...]
};

However, using kcalloc() is more appropriate [1] and improves
readability. This patch has no effect on runtime behavior.

Link: https://github.com/KSPP/linux/issues/162 [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Signed-off-by: Erick Archer <erick.archer@...look.com>
---
Changes in v2:
- Add the "Reviewed-by:" tag.
- Rebase against linux-next.

Previous versions:
v1 -> https://lore.kernel.org/linux-hardening/20240128115236.4791-1-erick.archer@gmx.com/

Hi everyone,

This patch seems to be lost. Gustavo reviewed it on January 30, 2024
but the patch has not been applied since.

Thanks,
Erick
---
 drivers/dma/amba-pl08x.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index fbf048f432bf..73a5cfb4da8a 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -2855,8 +2855,8 @@ static int pl08x_probe(struct amba_device *adev, const struct amba_id *id)
 	}
 
 	/* Initialize physical channels */
-	pl08x->phy_chans = kzalloc((vd->channels * sizeof(*pl08x->phy_chans)),
-			GFP_KERNEL);
+	pl08x->phy_chans = kcalloc(vd->channels, sizeof(*pl08x->phy_chans),
+				   GFP_KERNEL);
 	if (!pl08x->phy_chans) {
 		ret = -ENOMEM;
 		goto out_no_phychans;
-- 
2.25.1