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    SubjectRe: [PATCH] kobject_set_name_vargs memory leak
    On (06/26/09 07:49), Greg KH wrote:
    > Date: Fri, 26 Jun 2009 07:49:49 -0700
    > From: Greg KH <gregkh@suse.de>
    > To: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
    > Cc: Kay Sievers <kay.sievers@vrfy.org>,
    > "Eric W. Biederman" <ebiederm@xmission.com>,
    > linux-kernel@vger.kernel.org
    > Subject: Re: [PATCH] kobject_set_name_vargs memory leak
    > User-Agent: Mutt/1.5.19 (2009-01-05)
    >
    > On Fri, Jun 26, 2009 at 05:36:52PM +0300, Sergey Senozhatsky wrote:
    > > Hello.
    > > I suppose this patch fixes memory leak in kobject.c
    > > Correct me if I'm wrong.
    > > Thanks.
    > > -----------
    > >
    > > Fix memory leak when kobject_set_name_vargs returns -ENOMEM.
    > >
    > > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
    > > ---
    > > diff --git a/lib/kobject.c b/lib/kobject.c
    > > index b512b74..922cd8c 100644
    > > --- a/lib/kobject.c
    > > +++ b/lib/kobject.c
    > > @@ -222,8 +222,10 @@ int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
    > > return 0;
    > >
    > > kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
    > > - if (!kobj->name)
    > > + if (!kobj->name) {
    > > + kfree(old_name);
    > > return -ENOMEM;
    > > + }
    >
    > We've been through this before (search lkml archives). If kvasprintf
    > fails, then we don't want to free old_name, as the caller might want to
    > do something with it.
    >
    Hello Greg,

    int kobject_set_name_vargs.... {
    const char *old_name = kobj->name;

    old_name is local variable.

    In the following lines we overwrite kobject->name.

    kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
    if (!kobj->name)
    return -ENOMEM;

    It's not clear to me how we can do anything (including kfree) with old_name after 'return -ENOMEM'.

    Well, I'll try to search lklm.
    Thanks.


    > Or something along those lines, I can't remember the exact reasoning
    > this early in the morning.
    >
    > Kay, do you remember?
    >
    > thanks,
    >
    > greg k-h
    >

    Sergey


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