Re: [PATCH] ARM: cpuidle: Avoid memleak if init fail

[Leo Yan <leo.yan@linaro.org>]

On Fri, Sep 01, 2017 at 07:49:29AM +0200, Stefan Wahren wrote:
> Hi Leo,
> 
> > Leo Yan <leo.yan@linaro.org> hat am 1. September 2017 um 03:33 geschrieben:
> > 
> > 
> > Hi Stefan,
> > 
> > On Thu, Aug 31, 2017 at 10:24:36PM +0200, Stefan Wahren wrote:
> > > In case there are no DT idle states defined or
> > > cpuidle_register_driver() fails, the copy of the idle driver is leaked:
> > > 
> > >     unreferenced object 0xede0dc00 (size 1024):
> > >     comm "swapper/0", pid 1, jiffies 4294937431 (age 744.510s)
> > >     hex dump (first 32 bytes):
> > >     94 9e 0b c1 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > >     57 46 49 00 00 00 00 00 00 00 00 00 00 00 00 00 WFI.............
> > >     backtrace:
> > >     [<c1295f04>] arm_idle_init+0x44/0x1ac
> > >     [<c0301e6c>] do_one_initcall+0x3c/0x16c
> > >     [<c1200d70>] kernel_init_freeable+0x110/0x1d0
> > >     [<c0cb3624>] kernel_init+0x8/0x114
> > >     [<c0307a98>] ret_from_fork+0x14/0x3c
> > > 
> > > So fix this by freeing the unregistered copy in error case.
> > > 
> > > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> > > Fixes: d50a7d8acd78 ("ARM: cpuidle: Support asymmetric idle definition")
> > > ---
> > >  drivers/cpuidle/cpuidle-arm.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
> > > index 7080c38..52a7505 100644
> > > --- a/drivers/cpuidle/cpuidle-arm.c
> > > +++ b/drivers/cpuidle/cpuidle-arm.c
> > > @@ -104,13 +104,13 @@ static int __init arm_idle_init(void)
> > >  		ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
> > >  		if (ret <= 0) {
> > >  			ret = ret ? : -ENODEV;
> > > -			goto out_fail;
> > > +			goto init_fail;
> > >  		}
> > >  
> > >  		ret = cpuidle_register_driver(drv);
> > >  		if (ret) {
> > >  			pr_err("Failed to register cpuidle driver\n");
> > > -			goto out_fail;
> > > +			goto init_fail;
> > >  		}
> > >  
> > >  		/*
> > > @@ -149,6 +149,8 @@ static int __init arm_idle_init(void)
> > >  	}
> > >  
> > >  	return 0;
> > > +init_fail:
> > > +	kfree(drv);
> > 
> > The below loop only releases resource for previous CPUs, so should check
> > two variables 'drv' and 'dev'. If 'dev != NULL', we also need to release
> > it.
> 
> i cannot see a leak for 'dev', because this is already handled in the error case of cpuidle_register_device before jumping to out_fail. I agree this isn't consistent, but this is a fix which should go to stable. So only necessary changes.

You are right, so please ignore my comment.

BTW, to avoid missing anything, are you working on the second
fixing to correct the previous CPU resourcee releasing? Actually
I think you are welcome to work on the second fixing, but if
not I will take the second fixing with rebasing your patch.

Thanks,
Leo Yan