linux-kernel - [PATCH] ice: Prefer kcalloc over open coded arithmetic

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Date:   Sun,  5 Sep 2021 08:50:20 +0200
From:   Len Baker <len.baker@....com>
To:     Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Len Baker <len.baker@....com>, Kees Cook <keescook@...omium.org>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ice: Prefer kcalloc over open coded arithmetic

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.

In this case this is not actually dynamic sizes: both sides of the
multiplication are constant values. However it is best to refactor this
anyway, just to keep the open-coded math idiom out of code.

So, use the purpose specific kcalloc() function instead of the argument
size * count 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@....com>
---
 drivers/net/ethernet/intel/ice/ice_arfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_arfs.c b/drivers/net/ethernet/intel/ice/ice_arfs.c
index 88d98c9e5f91..3071b8e79499 100644
--- a/drivers/net/ethernet/intel/ice/ice_arfs.c
+++ b/drivers/net/ethernet/intel/ice/ice_arfs.c
@@ -513,7 +513,7 @@ void ice_init_arfs(struct ice_vsi *vsi)
 	if (!vsi || vsi->type != ICE_VSI_PF)
 		return;

-	arfs_fltr_list = kzalloc(sizeof(*arfs_fltr_list) * ICE_MAX_ARFS_LIST,
+	arfs_fltr_list = kcalloc(ICE_MAX_ARFS_LIST, sizeof(*arfs_fltr_list),
 				 GFP_KERNEL);
 	if (!arfs_fltr_list)
 		return;
--
2.25.1