lkml.org 
[lkml]   [2021]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] ASoC: da7219: Fix an out-of-bound read in an error handling path
Date
Le 23/06/2021 à 11:46, Dan Carpenter a écrit :
> On Wed, Jun 23, 2021 at 07:22:45AM +0200, Christophe JAILLET wrote:
>> If 'of_clk_add_hw_provider()' fails, the previous 'for' loop will have
>> run completely and 'i' is know to be 'DA7219_DAI_NUM_CLKS'.
>>
>> In such a case, there will be an out-of-bounds access when using
>> 'da7219->dai_clks_lookup[i]' and '&da7219->dai_clks_hw[i]'.
>>
>> To avoid that, add a new label, 'err_free_all', which set the expected
>> value of 'i' in such a case.
>>
>> Fixes: 78013a1cf297 ("ASoC: da7219: Fix clock handling around codec level probe")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>> ---
>> sound/soc/codecs/da7219.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
>> index 13009d08b09a..1e8b491d1fd3 100644
>> --- a/sound/soc/codecs/da7219.c
>> +++ b/sound/soc/codecs/da7219.c
>> @@ -2204,12 +2204,14 @@ static int da7219_register_dai_clks(struct snd_soc_component *component)
>> da7219->clk_hw_data);
>> if (ret) {
>> dev_err(dev, "Failed to register clock provider\n");
>> - goto err;
>> + goto err_free_all;
>> }
>> }
>>
>> return 0;
>>
>> +err_free_all:
>> + i = DA7219_DAI_NUM_CLKS - 1;
>> err:
>> do {
>> if (da7219->dai_clks_lookup[i])
>
> This do while statement is wrong and it leads to potentially calling
> clk_hw_unregister() on clks that haven't been registered.

Obviously right.

Thanks for the review Dan.
I'll send a v2 in the coming days.

CJ
>
> I think that calling clk_hw_unregister() on unregistered clocks is
> supposed to okay but I found a case where it leads to a WARN_ON()
> (Nothing else harmful). It's in __clk_register() if the alloc_clk()
> fails:
>
> hw->clk = alloc_clk(core, NULL, NULL);
> if (IS_ERR(hw->clk)) {
> ret = PTR_ERR(hw->clk);
> goto fail_create_clk; // <- forgot to set hw->clk = NULL
> }
>
> The better way to handle errors from loops is to clean up partial
> iterations before doing the goto. So add a clk_hw_unregister() if the
> dai_clk_lookup = clkdev_hw_create() assignment fails. Then use a
> while (--i >= 0) loop in the unwind section:
>
> err_free_all:
> i = DA7219_DAI_NUM_CLKS;
> err:
> while (--i >= 0) {
>
> regards,
> dan carpenter
>
>


\
 
 \ /
  Last update: 2021-06-23 23:14    [W:0.630 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site