* [patch] ALSA: bits vs bytes bug in snd_card_create()
@ 2014-01-23 8:21 Dan Carpenter
2014-01-23 8:36 ` Takashi Iwai
2014-01-23 8:55 ` walter harms
0 siblings, 2 replies; 6+ messages in thread
From: Dan Carpenter @ 2014-01-23 8:21 UTC (permalink / raw)
To: Jaroslav Kysela; +Cc: Takashi Iwai, Yacine Belkadi, alsa-devel, kernel-janitors
The test here is intended intended to prevent shift wrapping bugs when
we do "1U << idx2". We should consider the number of bits in a u32
instead of the number of bytes.
Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
WARNING: Please check this one carefully because I might be wrong.
diff --git a/sound/core/init.c b/sound/core/init.c
index 1351f22f651c..e9e3db321e64 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid,
if (idx < 0) {
for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
/* idx = -1 = 0xffff means: take any free slot */
- if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
+ if (idx2 < 32 && !(idx & (1U << idx2)))
continue;
if (!test_bit(idx2, snd_cards_lock)) {
if (!slots[idx2] || !*slots[idx2]) {
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [patch] ALSA: bits vs bytes bug in snd_card_create()
2014-01-23 8:21 [patch] ALSA: bits vs bytes bug in snd_card_create() Dan Carpenter
@ 2014-01-23 8:36 ` Takashi Iwai
2014-01-23 10:48 ` Takashi Iwai
2014-01-23 8:55 ` walter harms
1 sibling, 1 reply; 6+ messages in thread
From: Takashi Iwai @ 2014-01-23 8:36 UTC (permalink / raw)
To: Dan Carpenter
Cc: Jaroslav Kysela, Yacine Belkadi, alsa-devel, kernel-janitors
At Thu, 23 Jan 2014 11:21:28 +0300,
Dan Carpenter wrote:
>
> The test here is intended intended to prevent shift wrapping bugs when
> we do "1U << idx2". We should consider the number of bits in a u32
> instead of the number of bytes.
>
> Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> WARNING: Please check this one carefully because I might be wrong.
You're correct. I obviously didn't test more than 4.
Applied (with Cc to stable) now, thanks.
Takashi
>
> diff --git a/sound/core/init.c b/sound/core/init.c
> index 1351f22f651c..e9e3db321e64 100644
> --- a/sound/core/init.c
> +++ b/sound/core/init.c
> @@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid,
> if (idx < 0) {
> for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
> /* idx = -1 = 0xffff means: take any free slot */
> - if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
> + if (idx2 < 32 && !(idx & (1U << idx2)))
> continue;
> if (!test_bit(idx2, snd_cards_lock)) {
> if (!slots[idx2] || !*slots[idx2]) {
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] ALSA: bits vs bytes bug in snd_card_create()
2014-01-23 8:21 [patch] ALSA: bits vs bytes bug in snd_card_create() Dan Carpenter
2014-01-23 8:36 ` Takashi Iwai
@ 2014-01-23 8:55 ` walter harms
2014-01-23 9:02 ` Takashi Iwai
1 sibling, 1 reply; 6+ messages in thread
From: walter harms @ 2014-01-23 8:55 UTC (permalink / raw)
To: Dan Carpenter
Cc: Jaroslav Kysela, Takashi Iwai, Yacine Belkadi, alsa-devel,
kernel-janitors
Am 23.01.2014 09:21, schrieb Dan Carpenter:
> The test here is intended intended to prevent shift wrapping bugs when
> we do "1U << idx2". We should consider the number of bits in a u32
> instead of the number of bytes.
>
> Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> WARNING: Please check this one carefully because I might be wrong.
>
> diff --git a/sound/core/init.c b/sound/core/init.c
> index 1351f22f651c..e9e3db321e64 100644
> --- a/sound/core/init.c
> +++ b/sound/core/init.c
> @@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid,
> if (idx < 0) {
> for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
> /* idx = -1 = 0xffff means: take any free slot */
> - if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
> + if (idx2 < 32 && !(idx & (1U << idx2)))
> continue;
> if (!test_bit(idx2, snd_cards_lock)) {
> if (!slots[idx2] || !*slots[idx2]) {
> --
Funny bug,
to be 100% sure you could multiply by CHAR_BIT ;)
other code simple does (1UL << (nr & 31))
on the other side a check like:
#if SNDRV_CARDS > 32
# error to much sound
#endif
whould give the user a hint what is going on instead of silently ignoring
that error.
re,
wh
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] ALSA: bits vs bytes bug in snd_card_create()
2014-01-23 8:55 ` walter harms
@ 2014-01-23 9:02 ` Takashi Iwai
2014-01-23 9:27 ` walter harms
0 siblings, 1 reply; 6+ messages in thread
From: Takashi Iwai @ 2014-01-23 9:02 UTC (permalink / raw)
To: wharms
Cc: Dan Carpenter, Jaroslav Kysela, Yacine Belkadi, alsa-devel,
kernel-janitors
At Thu, 23 Jan 2014 09:55:31 +0100,
walter harms wrote:
>
>
> Am 23.01.2014 09:21, schrieb Dan Carpenter:
> > The test here is intended intended to prevent shift wrapping bugs when
> > we do "1U << idx2". We should consider the number of bits in a u32
> > instead of the number of bytes.
> >
> > Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > WARNING: Please check this one carefully because I might be wrong.
> >
> > diff --git a/sound/core/init.c b/sound/core/init.c
> > index 1351f22f651c..e9e3db321e64 100644
> > --- a/sound/core/init.c
> > +++ b/sound/core/init.c
> > @@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid,
> > if (idx < 0) {
> > for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
> > /* idx = -1 = 0xffff means: take any free slot */
> > - if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
> > + if (idx2 < 32 && !(idx & (1U << idx2)))
> > continue;
> > if (!test_bit(idx2, snd_cards_lock)) {
> > if (!slots[idx2] || !*slots[idx2]) {
> > --
>
> Funny bug,
> to be 100% sure you could multiply by CHAR_BIT ;)
>
> other code simple does (1UL << (nr & 31))
> on the other side a check like:
>
> #if SNDRV_CARDS > 32
> # error to much sound
> #endif
>
> whould give the user a hint what is going on instead of silently ignoring
> that error.
SNDRV_CARDS can be more than 32. That's why the check was
introduced.
Takashi
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] ALSA: bits vs bytes bug in snd_card_create()
2014-01-23 9:02 ` Takashi Iwai
@ 2014-01-23 9:27 ` walter harms
0 siblings, 0 replies; 6+ messages in thread
From: walter harms @ 2014-01-23 9:27 UTC (permalink / raw)
To: Takashi Iwai
Cc: Dan Carpenter, Jaroslav Kysela, Yacine Belkadi, alsa-devel,
kernel-janitors
Am 23.01.2014 10:02, schrieb Takashi Iwai:
> At Thu, 23 Jan 2014 09:55:31 +0100,
> walter harms wrote:
>>
>>
>> Am 23.01.2014 09:21, schrieb Dan Carpenter:
>>> The test here is intended intended to prevent shift wrapping bugs when
>>> we do "1U << idx2". We should consider the number of bits in a u32
>>> instead of the number of bytes.
>>>
>>> Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
>>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>> ---
>>> WARNING: Please check this one carefully because I might be wrong.
>>>
>>> diff --git a/sound/core/init.c b/sound/core/init.c
>>> index 1351f22f651c..e9e3db321e64 100644
>>> --- a/sound/core/init.c
>>> +++ b/sound/core/init.c
>>> @@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid,
>>> if (idx < 0) {
>>> for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
>>> /* idx = -1 = 0xffff means: take any free slot */
>>> - if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
>>> + if (idx2 < 32 && !(idx & (1U << idx2)))
>>> continue;
>>> if (!test_bit(idx2, snd_cards_lock)) {
>>> if (!slots[idx2] || !*slots[idx2]) {
>>> --
>>
>> Funny bug,
>> to be 100% sure you could multiply by CHAR_BIT ;)
>>
>> other code simple does (1UL << (nr & 31))
>> on the other side a check like:
>>
>> #if SNDRV_CARDS > 32
>> # error to much sound
>> #endif
>>
>> whould give the user a hint what is going on instead of silently ignoring
>> that error.
>
> SNDRV_CARDS can be more than 32. That's why the check was
> introduced.
>
yes of cause, but so far i understand this code will do "continue" if SNDRV_CARDS
is more that 31, no warning.
(warning Start academic discussion):
If anyone ever has more that 31 soundcard he will wonder why 31 are working but the
rest will remain silent. It would be nice to have a idea that there is an internal limit
and it is not sufficient to change SNDRV_CARDS from 8 to 256. (did i understand the code
correctly ?) and there is no warning.
re,
wh
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] ALSA: bits vs bytes bug in snd_card_create()
2014-01-23 8:36 ` Takashi Iwai
@ 2014-01-23 10:48 ` Takashi Iwai
0 siblings, 0 replies; 6+ messages in thread
From: Takashi Iwai @ 2014-01-23 10:48 UTC (permalink / raw)
To: Dan Carpenter
Cc: Jaroslav Kysela, Yacine Belkadi, alsa-devel, kernel-janitors
At Thu, 23 Jan 2014 09:36:24 +0100,
Takashi Iwai wrote:
>
> At Thu, 23 Jan 2014 11:21:28 +0300,
> Dan Carpenter wrote:
> >
> > The test here is intended intended to prevent shift wrapping bugs when
> > we do "1U << idx2". We should consider the number of bits in a u32
> > instead of the number of bytes.
> >
> > Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > WARNING: Please check this one carefully because I might be wrong.
>
> You're correct. I obviously didn't test more than 4.
> Applied (with Cc to stable) now, thanks.
I found there is another place doing it wrongly (a few lines above
there), so fixed similarly in the same patch.
(And, yes, the code should be refactored; the patch will be sent soon
later.)
Takashi
-- 8< --
From: Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH] ALSA: bits vs bytes bug in snd_card_create()
The test here is intended intended to prevent shift wrapping bugs when
we do "1U << idx2". We should consider the number of bits in a u32
instead of the number of bytes.
[fix another chunk similarly by tiwai]
Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/core/init.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/core/init.c b/sound/core/init.c
index 1351f22f651c..e3c93cd77ee7 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -170,7 +170,7 @@ int snd_card_create(int idx, const char *xid,
if (idx < 0) {
for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
/* idx = -1 = 0xffff means: take any free slot */
- if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
+ if (idx2 < 32 && !(idx & (1U << idx2)))
continue;
if (!test_bit(idx2, snd_cards_lock)) {
if (module_slot_match(module, idx2)) {
@@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid,
if (idx < 0) {
for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) {
/* idx = -1 = 0xffff means: take any free slot */
- if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
+ if (idx2 < 32 && !(idx & (1U << idx2)))
continue;
if (!test_bit(idx2, snd_cards_lock)) {
if (!slots[idx2] || !*slots[idx2]) {
--
1.8.5.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
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2014-01-23 8:21 [patch] ALSA: bits vs bytes bug in snd_card_create() Dan Carpenter
2014-01-23 8:36 ` Takashi Iwai
2014-01-23 10:48 ` Takashi Iwai
2014-01-23 8:55 ` walter harms
2014-01-23 9:02 ` Takashi Iwai
2014-01-23 9:27 ` walter harms
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