Re: [PATCH] ALSA: pci: lx6464es: fix a debug loop

[Dan Carpenter <error27@gmail.com>]

On Thu, Jan 26, 2023 at 01:53:01PM +0100, Takashi Iwai wrote:
> On Thu, 26 Jan 2023 10:30:02 +0100,
> Dan Carpenter wrote:
> > 
> > This loop accidentally reuses the "i" iterator for both the inside and
> > the outside loop.  The value of MAX_STREAM_BUFFER is 5.  I believe that
> > chip->rmh.stat_len is in the 2-12 range.  If the value of .stat_len is
> > 4 or more then it will loop exactly one time, but if it's less then it
> > is a forever loop.
> > 
> > Fixes: 8e6320064c33 ("ALSA: lx_core: Remove useless #if 0 .. #endif")
> > Signed-off-by: Dan Carpenter <error27@gmail.com>
> > ---
> >  sound/pci/lx6464es/lx_core.c | 12 +++++-------
> >  1 file changed, 5 insertions(+), 7 deletions(-)
> > 
> > diff --git a/sound/pci/lx6464es/lx_core.c b/sound/pci/lx6464es/lx_core.c
> > index d3f58a3d17fb..7c1b380a54c0 100644
> > --- a/sound/pci/lx6464es/lx_core.c
> > +++ b/sound/pci/lx6464es/lx_core.c
> > @@ -493,13 +493,11 @@ int lx_buffer_ask(struct lx6464es *chip, u32 pipe, int is_capture,
> >  		dev_dbg(chip->card->dev,
> >  			"CMD_08_ASK_BUFFERS: needed %d, freed %d\n",
> >  			    *r_needed, *r_freed);
> > -		for (i = 0; i < MAX_STREAM_BUFFER; ++i) {
> > -			for (i = 0; i != chip->rmh.stat_len; ++i)
> > -				dev_dbg(chip->card->dev,
> > -					"  stat[%d]: %x, %x\n", i,
> > -					    chip->rmh.stat[i],
> > -					    chip->rmh.stat[i] & MASK_DATA_SIZE);
> > -		}
> > +		for (i = 0; i < chip->rmh.stat_len; ++i)
> 
> Judging from the previous lines, the access over MAX_STREAM_BUFFER
> might be unsafe.  So I guess a more safer change would be something
> like:
> 
> 		for (i = 0; i < MAX_STREAM_BUFFER && chip->rmh.stat_len; ++i)

&& i < chip->rmh.stat_len

TBH, I'd prefer to just delete all this code since it used be ifdef 0.

But I'll resend as you have suggested.

regards,
dan carpenter