From: Souptick Joarder <jrdr.linux@gmail.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org,
Linux-MM <linux-mm@kvack.org>,
Miles Chen <miles.chen@mediatek.com>,
linux-mediatek@lists.infradead.org,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm/gup: fix null pointer dereference detected by coverity
Date: Wed, 15 Apr 2020 01:25:07 +0530 [thread overview]
Message-ID: <CAFqt6zYztssQEgMJtafr_ZdMYvBwAU-BZ4Z4tOWQPJ6eFnHq2Q@mail.gmail.com> (raw)
In-Reply-To: <20200407181908.GB94792@iweiny-DESK2.sc.intel.com>
On Tue, Apr 7, 2020 at 11:49 PM Ira Weiny <ira.weiny@intel.com> wrote:
>
> On Tue, Apr 07, 2020 at 05:51:07PM +0800, Miles Chen wrote:
> > In fixup_user_fault(), it is possible that unlocked is NULL,
> > so we should test unlocked before using it.
> >
> > For example, in arch/arc/kernel/process.c, NULL is passed
> > to fixup_user_fault().
> >
> > SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new)
> > {
> > ...
> > ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr,
> > FAULT_FLAG_WRITE, NULL);
> > ...
> > }
> >
> > Fixes: 4a9e1cda2748 ("mm: bring in additional flag for fixup_user_fault to signal unlock")
> > Signed-off-by: Miles Chen <miles.chen@mediatek.com>
>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
>
> > ---
> > mm/gup.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/gup.c b/mm/gup.c
> > index da3e03185144..a68d11dc232d 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -1230,7 +1230,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
> > if (ret & VM_FAULT_RETRY) {
> > down_read(&mm->mmap_sem);
> > if (!(fault_flags & FAULT_FLAG_TRIED)) {
> > - *unlocked = true;
> > + if (unlocked)
> > + *unlocked = true;
> > fault_flags |= FAULT_FLAG_TRIED;
> > goto retry;
> > }
> > --
> > 2.18.0
>
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next prev parent reply other threads:[~2020-04-14 19:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 9:51 [PATCH] mm/gup: fix null pointer dereference detected by coverity Miles Chen
2020-04-07 18:19 ` Ira Weiny
2020-04-14 19:55 ` Souptick Joarder [this message]
2020-04-15 0:08 ` Andrew Morton
2020-04-15 1:53 ` Miles Chen
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