2014-04-09 10:45:55

by Daeseok Youn

Subject: [PATCH] staging: speakup: fix misuse of kstrtol() in handle_goto()

A string of goto_buf has a number followed by x or y.
e.g. "3x" means move 3 lines down.
The kstrtol() returns an error(-EINVAL) with this string so
go_pos has unsigned a value of that error.
And also "*cp" has not expected value.

And fix sparse warnings:
drivers/staging/speakup/main.c:1901 handle_goto() warn:
unsigned '(speakup_console[vc->vc_num]->go_pos)' is never less than zero.
drivers/staging/speakup/main.c:1911 handle_goto() warn:
unsigned '(speakup_console[vc->vc_num]->go_pos)' is never less than zero.

Signed-off-by: Daeseok Youn <[email protected]>
---
drivers/staging/speakup/main.c | 18 +++++++++---------
1 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/speakup/main.c b/drivers/staging/speakup/main.c
index ef5933b..3b6e535 100644
--- a/drivers/staging/speakup/main.c
+++ b/drivers/staging/speakup/main.c
@@ -1855,8 +1855,9 @@ static int handle_goto(struct vc_data *vc, u_char type, u_char ch, u_short key)
{
static u_char goto_buf[8];
static int num;
- int maxlen, go_pos;
+ int maxlen;
char *cp;
+
if (type == KT_SPKUP && ch == SPEAKUP_GOTO)
goto do_goto;
if (type == KT_LATIN && ch == '\n')
@@ -1891,25 +1892,24 @@ oops:
spk_special_handler = NULL;
return 1;
}
- go_pos = kstrtol(goto_buf, 10, (long *)&cp);
- goto_pos = (u_long) go_pos;
+
+ goto_pos = simple_strtoul(goto_buf, &cp, 10);
+
if (*cp == 'x') {
if (*goto_buf < '0')
goto_pos += spk_x;
- else
+ else if (goto_pos > 0)
goto_pos--;
- if (goto_pos < 0)
- goto_pos = 0;
+
if (goto_pos >= vc->vc_cols)
goto_pos = vc->vc_cols - 1;
goto_x = 1;
} else {
if (*goto_buf < '0')
goto_pos += spk_y;
- else
+ else if (goto_pos > 0)
goto_pos--;
- if (goto_pos < 0)
- goto_pos = 0;
+
if (goto_pos >= vc->vc_rows)
goto_pos = vc->vc_rows - 1;
goto_x = 0;
--
1.7.4.4

2014-04-09 11:39:25

by Dan Carpenter

Subject: Re: [PATCH] staging: speakup: fix misuse of kstrtol() in handle_goto()

On Wed, Apr 09, 2014 at 07:45:46PM +0900, Daeseok Youn wrote:
>
> A string of goto_buf has a number followed by x or y.
> e.g. "3x" means move 3 lines down.
> The kstrtol() returns an error(-EINVAL) with this string so
> go_pos has unsigned a value of that error.
> And also "*cp" has not expected value.
>

Good catch. This was introduced when we changed the simple_strtoul() to
kstrtol().

Reviewed-by: Dan Carpenter <[email protected]>

Did you find this bug by testing or through reading the code?

regards,
dan carpenter

2014-04-09 13:53:55

by Daeseok Youn

Subject: Re: [PATCH] staging: speakup: fix misuse of kstrtol() in handle_goto()

2014-04-09 20:39 GMT+09:00, Dan Carpenter <[email protected]>:
> On Wed, Apr 09, 2014 at 07:45:46PM +0900, Daeseok Youn wrote:
>>
>> A string of goto_buf has a number followed by x or y.
>> e.g. "3x" means move 3 lines down.
>> The kstrtol() returns an error(-EINVAL) with this string so
>> go_pos has unsigned a value of that error.
>> And also "*cp" has not expected value.
>>
>
> Good catch. This was introduced when we changed the simple_strtoul() to
> kstrtol().

Thanks! :-)

>
> Reviewed-by: Dan Carpenter <[email protected]>
>
> Did you find this bug by testing or through reading the code?
Actually, I couldn't test. I have looked the code for checking sparse
warnings and found this bug.

Regards,
Daeseok Youn

>
> regards,
> dan carpenter
>
>