2019-04-26 22:23:49

by Colin King

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

From: Colin Ian King <[email protected]>

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 <[email protected]>
---
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

2019-04-27 06:31:28

by Masahiro Yamada

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 <[email protected]> wrote:
>
> From: Colin Ian King <[email protected]>
>
> 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 <[email protected]>
> ---
> 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

2019-04-28 11:04:06

by Gabriel Krisman Bertazi

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

Masahiro Yamada <[email protected]> writes:

> Forwarding because this file is not in my tree.
>
>
>
>
>
> On Sat, Apr 27, 2019 at 7:22 AM Colin King <[email protected]> wrote:
>>
>> From: Colin Ian King <[email protected]>
>>
>> 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 <[email protected]>


Acked-by: Gabriel Krisman Bertazi <[email protected]>

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

2019-04-28 13:25:17

by Theodore Ts'o

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

On Sun, Apr 28, 2019 at 07:02:45AM -0400, Gabriel Krisman Bertazi wrote:
> > On Sat, Apr 27, 2019 at 7:22 AM Colin King <[email protected]> wrote:
> >>
> >> From: Colin Ian King <[email protected]>
> >>
> >> 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 <[email protected]>
>
> Acked-by: Gabriel Krisman Bertazi <[email protected]>
>
> Ted, can you pick this up directly for now?

Ack, I've merged it into the the patch "unicode: introduce UTF-8
character database".

- Ted