Re: memory leak in kobject_set_name_vargs (2)

[Qian Cai <cai@lca.pw>]

> On Jul 26, 2019, at 10:29 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
> On Fri, Jul 26, 2019 at 4:26 PM syzbot
> <syzbot+ad8ca40ecd77896d51e2@syzkaller.appspotmail.com> wrote:
>> 
>> syzbot has bisected this bug to:
>> 
>> commit 0e034f5c4bc408c943f9c4a06244415d75d7108c
>> Author: Linus Torvalds <torvalds@linux-foundation.org>
>> Date:   Wed May 18 18:51:25 2016 +0000
>> 
>>     iwlwifi: fix mis-merge that breaks the driver
> 
> While this bisection looks more likely than the other syzbot entry
> that bisected to a version change, I don't think it is correct eitger.
> 
> The bisection ended up doing a lot of "git bisect skip" because of the
> 
>    undefined reference to `nf_nat_icmp_reply_translation'
> 
> issue. Also, the memory leak doesn't seem to be entirely reliable:
> when the bisect does 10 runs to verify that some test kernel is bad,
> there are a couple of cases where only one or two of the ten run
> failed.
> 
> Which makes me wonder if one or two of the "everything OK" runs were
> actually buggy, but just happened to have all ten pass…

Real bisection should point to,

8ed633b9baf9e (“Revert "net-sysfs: Fix memory leak in netdev_register_kobject”")

I did encounter those memory leak and comes up with a similar fix in,

6b70fc94afd1 ("net-sysfs: Fix memory leak in netdev_register_kobject”)

but those error handling paths are tricky that seems nobody did much testing there, so it will
keep hitting other bugs in upper functions.