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

[Takashi Iwai <tiwai@suse.de>]

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)

Care to resubmit with it?


Thanks!

Takashi