On 11/30/17 08:37, Frank Rowand wrote:
> Hi Colin, Rob,
>
> On 11/30/17 07:18, Colin Ian King wrote:
>> On 30/11/17 12:14, Frank Rowand wrote:
>>> On 11/29/17 14:17, Colin King wrote:
>>>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>>
>>>> Currently if the call to of_resolve_phandles fails then then ovcs
>>>> is not kfree'd on the error exit path. Rather than try and make
>>>> the clean up exit path more convoluted, fix this by just kfree'ing
>>>> ovcs at the point of error detection and exit via the same exit
>>>> path.
>>>>
>>>> Detected by CoverityScan, CID#1462296 ("Resource Leak")
>>>>
>>>> Fixes: f948d6d8b792 ("of: overlay: avoid race condition between applying multiple overlays")
>>>> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>> ---
>>>> drivers/of/overlay.c | 4 +++-
>>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>>>> index 53bc9e3f0b98..6c8efe7d8cbb 100644
>>>> --- a/drivers/of/overlay.c
>>>> +++ b/drivers/of/overlay.c
>>>> @@ -708,8 +708,10 @@ int of_overlay_apply(struct device_node *tree, int *ovcs_id)
>>>> of_overlay_mutex_lock();
>>>>
>>>> ret = of_resolve_phandles(tree);
>>>> - if (ret)
>>>> + if (ret) {
>>>> + kfree(ovcs);
>>>> goto err_overlay_unlock;
>>>> + }
>>>>
>>>> mutex_lock(&of_mutex);
>>>>
>>>>
>>>
>>> False coverity warning. ovcs is freed in free_overlay_changeset().
>>>
>>
>> The error exit path is via err_overlay_unlock:
>>
>> err_overlay_unlock:
>> of_overlay_mutex_unlock();
>>
>> out:
>> pr_debug("%s() err=%d\n", __func__, ret);
>>
>> return ret;
>>
>> ..so there is no call to free_overlay_changeset there.
>>
>> Colin
>>
>
> OK, I was looking at 4.15-rc1. You must be looking at a later version where
> "[PATCH 1/2] of: overlay: Fix cleanup order in of_overlay_apply()" has been
> applied. Thanks for providing the extra details about the exit path so I
> could see that.
>
> Rob, I think that the fix for cleanup order was not the best way to fix that
> problem. A better method would have been to move "mutex_lock(&of_mutex);"
> up 5 lines, to just before calling of_reserve_phandles().
It is getting late (midnight my time), so I really should revisit this all
tomorrow. My last comment ("move ... up 5 lines") is probably wrong.
I'll look at this after some sleep.
> The problem
> found by coverity was caused by the "Fix cleanup order" patch.
>
> I can create that alternate fix if you would like, but I am traveling
> right now and don't want to submit a patch without boot testing, so
> there will be a slight delay.
>
> -Frank
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