linux-ext4 - [PATCH linux-next] ext4: use kcalloc instead of open coded arithmetic

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Date: Fri, 15 Dec 2023 21:43:02 +0800 (CST)
From: <yang.guang5@....com.cn>
To: <tytso@....edu>
Cc: <jiang.xuexin@....com.cn>, <chen.haonan2@....com.cn>, <cgel.zte@...il.com>,
        <adilger.kernel@...ger.ca>, <linux-ext4@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH linux-next] ext4: use kcalloc instead of open coded arithmetic

From: Yang Guang <yang.guang5@....com.cn>

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: Chen Haonan <chen.haonan2@....com.cn>
---
 fs/ext4/hash.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/hash.c b/fs/ext4/hash.c
index deabe29da7fb..7a9afac1597c 100644
--- a/fs/ext4/hash.c
+++ b/fs/ext4/hash.c
@@ -302,7 +302,7 @@ int ext4fs_dirhash(const struct inode *dir, const char *name, int len,

 	if (len && IS_CASEFOLDED(dir) &&
 	   (!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir))) {
-		buff = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);
+		buff = kcalloc(PATH_MAX, sizeof(char), GFP_KERNEL);
 		if (!buff)
 			return -ENOMEM;

-- 
2.25.1