Messages in this thread | | | Date | Thu, 21 Jul 2022 12:30:32 +0200 | Subject | Re: [PATCH] ASoC: qcom: q6dsp: Fix an off-by-one in q6adm_alloc_copp() | From | Christophe JAILLET <> |
| |
Le 21/07/2022 à 12:00, Dan Carpenter a écrit : > On Thu, Jul 21, 2022 at 11:02:22AM +0200, Christophe JAILLET wrote: >> find_first_zero_bit() returns MAX_COPPS_PER_PORT at max here. >> So 'idx' should be tested with ">=" or the test can't match. >> >> Fixes: 7b20b2be51e1 ("ASoC: qdsp6: q6adm: Add q6adm driver") >> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> >> --- >> sound/soc/qcom/qdsp6/q6adm.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/sound/soc/qcom/qdsp6/q6adm.c b/sound/soc/qcom/qdsp6/q6adm.c >> index 01f383888b62..1530e98df165 100644 >> --- a/sound/soc/qcom/qdsp6/q6adm.c >> +++ b/sound/soc/qcom/qdsp6/q6adm.c >> @@ -217,7 +217,7 @@ static struct q6copp *q6adm_alloc_copp(struct q6adm *adm, int port_idx) >> idx = find_first_zero_bit(&adm->copp_bitmap[port_idx], >> MAX_COPPS_PER_PORT); >> >> - if (idx > MAX_COPPS_PER_PORT) >> + if (idx >= MAX_COPPS_PER_PORT) >> return ERR_PTR(-EBUSY); > > Harshit asked me to write a Smatch check to prevent this bug in the > future. I got his email before I got your patch. :P Attached.
Well, well, well... Easy to say afterwards. You got 58 mins to write it. :).
> > sound/soc/qcom/qdsp6/q6adm.c:220 q6adm_alloc_copp() warn: impossible find_next_bit condition > > I'll probably try to make this check more generic, but even the simple > find_first_zero_bit() version will probably find bugs in the future and > it was pretty simple to write.
You could add find_last_bit(), find_next_zero_bit_le() and find_next_bit_le().
> > regards, > dan carpenter > >
A reduced version of mine was:
@@ expression e1, e2; statement S; @@ ( * e1 = find_first_bit(...); | * e1 = find_last_bit(...); | [... snip ...] ) ... if (e1 > e2) S
(and it takes only a few seconds to scan the whole kernel :) )
| |