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Message-ID: <5197939870d1867dd2131a8fdff8842b777c6016.camel@perches.com>
Subject: Re: [PATCH 1/5] fs/ntfs3: Use kmalloc_array over kmalloc with
 multiply
From:   Joe Perches <joe@perches.com>
To:     Kari Argillander <kari.argillander@gmail.com>,
        Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
        ntfs3@lists.linux.dev
Cc:     linux-kernel@vger.kernel.org
Date:   Tue, 31 Aug 2021 19:40:58 -0700
In-Reply-To: <20210831181505.1074767-2-kari.argillander@gmail.com>
References: <20210831181505.1074767-1-kari.argillander@gmail.com>
         <20210831181505.1074767-2-kari.argillander@gmail.com>
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On Tue, 2021-08-31 at 21:15 +0300, Kari Argillander wrote:
> If we do not use kmalloc_array we get checkpatch warning. It is also
> little safer if something goes wrong with coding.
[]
> diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
[]
> @@ -707,7 +707,7 @@ static struct NTFS_DE *hdr_find_e(const struct ntfs_index *indx,
> ?		u16 *ptr;
> ?		int new_slots = ALIGN(2 * nslots, 8);
> ?
> 
> -		ptr = kmalloc(sizeof(u16) * new_slots, GFP_NOFS);
> +		ptr = kmalloc_array(new_slots, sizeof(u16), GFP_NOFS);
> ?		if (ptr)
> ?			memcpy(ptr, offs, sizeof(u16) * max_idx);

This multiplication could also overflow.

Maybe use krealloc?