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

From: Gabriel Krisman Bertazi
Date: Sun Apr 28 2019 - 07:02:55 EST


Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> writes:

> Forwarding because this file is not in my tree.
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> On Sat, Apr 27, 2019 at 7:22 AM Colin King <colin.king@xxxxxxxxxxxxx> wrote:
>>
>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>
>> 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@xxxxxxxxxxxxx>


Acked-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>

Ted, can you pick this up directly for now?

>> ---
>> 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

--
Gabriel Krisman Bertazi