linux-kernel - Re: [PATCH][next] unicode: fix dereference of a potentially null pointer

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Message-ID: <CAK7LNATC5b9yx79sF55hw1X9vZTJK8H+WsLRfy81_chZYRgTYw@mail.gmail.com>
Date:   Sat, 27 Apr 2019 15:29:30 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Olaf Weber <olaf@....com>,
        Gabriel Krisman Bertazi <krisman@...labora.co.uk>,
        "Theodore Ts'o" <tytso@....edu>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Colin King <colin.king@...onical.com>,
        kernel-janitors@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][next] unicode: fix dereference of a potentially null pointer

Forwarding because this file is not in my tree.





On Sat, Apr 27, 2019 at 7:22 AM Colin King <colin.king@...onical.com> wrote:
>
> From: Colin Ian King <colin.king@...onical.com>
>
> The pointer 'tree' is deferenced when assigning pointer 'trie', however
> trie is being null checked a few lines later, so it could potentially
> be null. Fix the potential null pointer dereference by only dereferencing
> it after it has been null checked.
>
> Addresses-Coverity: ("Dereference before null check")
> Fixes: b08fcacaaaf4 ("unicode: introduce UTF-8 character database")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  scripts/mkutf8data.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/mkutf8data.c b/scripts/mkutf8data.c
> index 12ce94b43be6..0563ba679bbb 100644
> --- a/scripts/mkutf8data.c
> +++ b/scripts/mkutf8data.c
> @@ -2706,7 +2706,7 @@ static utf8leaf_t *utf8hangul(const char *str, unsigned char *hangul)
>  static utf8leaf_t *utf8nlookup(struct tree *tree, unsigned char *hangul,
>                                const char *s, size_t len)
>  {
> -       utf8trie_t      *trie = utf8data + tree->index;
> +       utf8trie_t      *trie;
>         int             offlen;
>         int             offset;
>         int             mask;
> @@ -2716,6 +2716,7 @@ static utf8leaf_t *utf8nlookup(struct tree *tree, unsigned char *hangul,
>                 return NULL;
>         if (len == 0)
>                 return NULL;
> +       trie = utf8data + tree->index;
>         node = 1;
>         while (node) {
>                 offlen = (*trie & OFFLEN) >> OFFLEN_SHIFT;
> --
> 2.20.1
>


--
Best Regards
Masahiro Yamada