linux-hardening - [PATCH 2/2] staging/rtl8192u: Prefer kcalloc over open coded arithmetic

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Date:   Sun, 22 Aug 2021 16:28:20 +0200
From:   Len Baker <len.baker@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Len Baker <len.baker@....com>, Kees Cook <keescook@...omium.org>,
        Michael Straube <straube.linux@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH 2/2] staging/rtl8192u: Prefer kcalloc over open coded arithmetic

Dynamic 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 purpose specific kcalloc() function instead of the argument
size * count in the kzalloc() function.

Signed-off-by: Len Baker <len.baker@....com>
---
 drivers/staging/rtl8192u/r819xU_phy.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/rtl8192u/r819xU_phy.c b/drivers/staging/rtl8192u/r819xU_phy.c
index ff6fe2ee3349..97f4d89500ae 100644
--- a/drivers/staging/rtl8192u/r819xU_phy.c
+++ b/drivers/staging/rtl8192u/r819xU_phy.c
@@ -1195,17 +1195,17 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel,
 	u8 e_rfpath;
 	bool ret;

-	pre_cmd = kzalloc(sizeof(*pre_cmd) * MAX_PRECMD_CNT, GFP_KERNEL);
+	pre_cmd = kcalloc(MAX_PRECMD_CNT, sizeof(*pre_cmd), GFP_KERNEL);
 	if (!pre_cmd)
 		return false;

-	post_cmd = kzalloc(sizeof(*post_cmd) * MAX_POSTCMD_CNT, GFP_KERNEL);
+	post_cmd = kcalloc(MAX_POSTCMD_CNT, sizeof(*post_cmd), GFP_KERNEL);
 	if (!post_cmd) {
 		kfree(pre_cmd);
 		return false;
 	}

-	rf_cmd = kzalloc(sizeof(*rf_cmd) * MAX_RFDEPENDCMD_CNT, GFP_KERNEL);
+	rf_cmd = kcalloc(MAX_RFDEPENDCMD_CNT, sizeof(*rf_cmd), GFP_KERNEL);
 	if (!rf_cmd) {
 		kfree(pre_cmd);
 		kfree(post_cmd);
--
2.25.1