From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, mgorman@suse.de,
andi@firstfloor.org, sasha.levin@oracle.com,
kirill.shutemov@linux.intel.com, aneesh.kumar@linux.vnet.ibm.com,
linux-mm@kvack.org
Subject: Re: [PATCH] mm/hugetlb.c: add NULL check of return value of huge_pte_offset
Date: Fri, 04 Apr 2014 20:04:09 -0400 [thread overview]
Message-ID: <533f488f.48c70e0a.4f2d.291eSMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <20140404150345.92400430db3111fe21df7c7f@linux-foundation.org>
On Fri, Apr 04, 2014 at 03:03:45PM -0700, Andrew Morton wrote:
> On Fri, 04 Apr 2014 14:43:33 -0400 Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> wrote:
>
> > huge_pte_offset() could return NULL, so we need NULL check to avoid
> > potential NULL pointer dereferences.
> >
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -2662,7 +2662,8 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
> > BUG_ON(huge_pte_none(pte));
> > spin_lock(ptl);
> > ptep = huge_pte_offset(mm, address & huge_page_mask(h));
> > - if (likely(pte_same(huge_ptep_get(ptep), pte)))
> > + if (likely(ptep &&
> > + pte_same(huge_ptep_get(ptep), pte)))
> > goto retry_avoidcopy;
> > /*
> > * race occurs while re-acquiring page table
> > @@ -2706,7 +2707,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
> > */
> > spin_lock(ptl);
> > ptep = huge_pte_offset(mm, address & huge_page_mask(h));
> > - if (likely(pte_same(huge_ptep_get(ptep), pte))) {
> > + if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
> > ClearPagePrivate(new_page);
> >
> > /* Break COW */
>
> Has anyone been hitting oopses here or was this from code inspection?
It's from code inspection. This is why I didn't CCed stable.
Naoya
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-04-05 0:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <533efd68.435fe00a.6936.ffffa5e7SMTPIN_ADDED_BROKEN@mx.google.com>
2014-04-04 22:03 ` Andrew Morton
2014-04-05 0:04 ` Naoya Horiguchi [this message]
2014-04-04 18:43 Naoya Horiguchi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=533f488f.48c70e0a.4f2d.291eSMTPIN_ADDED_BROKEN@mx.google.com \
--to=n-horiguchi@ah.jp.nec.com \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=sasha.levin@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox