From: Andrew Morton <akpm@linux-foundation.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: js1304@gmail.com, mgorman@techsingularity.net,
Minchan Kim <minchan@kernel.org>,
Alexander Potapenko <glider@google.com>,
Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Sasha Levin <sasha.levin@oracle.com>,
Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v3 7/9] mm/page_owner: avoid null pointer dereference
Date: Fri, 24 Jun 2016 13:19:44 -0700 [thread overview]
Message-ID: <20160624131944.cf98a963de76938246a27e13@linux-foundation.org> (raw)
In-Reply-To: <09cfe295-87d0-16d9-36ed-458378b3bd05@suse.cz>
On Fri, 17 Jun 2016 15:32:20 +0200 Vlastimil Babka <vbabka@suse.cz> wrote:
> On 06/17/2016 09:57 AM, js1304@gmail.com wrote:
> > From: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
> >
> > We have dereferenced page_ext before checking it. Lets check it first
> > and then used it.
> >
> > Link: http://lkml.kernel.org/r/1465249059-7883-1-git-send-email-sudipm.mukherjee@gmail.com
> > Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> Hmm, this is already in mmotm as
> http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_owner-use-stackdepot-to-store-stacktrace-fix.patch
>
> But imho it's fixing a problem not related to your patch, but something that the
> commit f86e4271978b missed. So it should separately go to 4.7 ASAP.
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Fixes: f86e4271978b ("mm: check the return value of lookup_page_ext for all call
> sites")
Thanks, I reordered Sudip's patch.
From: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: mm/page_owner: avoid null pointer dereference
We have dereferenced page_ext before checking it. Lets check it first
and then used it.
Fixes: f86e4271978b ("mm: check the return value of lookup_page_ext for all call sites")
Link: http://lkml.kernel.org/r/1465249059-7883-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/page_owner.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN mm/page_owner.c~mm-page_owner-use-stackdepot-to-store-stacktrace-fix mm/page_owner.c
--- a/mm/page_owner.c~mm-page_owner-use-stackdepot-to-store-stacktrace-fix
+++ a/mm/page_owner.c
@@ -207,13 +207,15 @@ void __dump_page_owner(struct page *page
.nr_entries = page_ext->nr_entries,
.entries = &page_ext->trace_entries[0],
};
- gfp_t gfp_mask = page_ext->gfp_mask;
- int mt = gfpflags_to_migratetype(gfp_mask);
+ gfp_t gfp_mask;
+ int mt;
if (unlikely(!page_ext)) {
pr_alert("There is not page extension available.\n");
return;
}
+ gfp_mask = page_ext->gfp_mask;
+ mt = gfpflags_to_migratetype(gfp_mask);
if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
pr_alert("page_owner info is not active (free page?)\n");
_
--
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next prev parent reply other threads:[~2016-06-24 20:19 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-17 7:57 [PATCH v3 0/9] reduce memory usage by page_owner js1304
2016-06-17 7:57 ` [PATCH v3 1/9] mm/compaction: split freepages without holding the zone lock js1304
2016-06-17 7:57 ` [PATCH v3 2/9] mm/page_owner: initialize page owner " js1304
2016-06-17 7:57 ` [PATCH v3 3/9] mm/page_owner: copy last_migrate_reason in copy_page_owner() js1304
2016-06-17 7:57 ` [PATCH v3 4/9] mm/page_owner: introduce split_page_owner and replace manual handling js1304
2016-06-17 7:57 ` [PATCH v3 5/9] tools/vm/page_owner: increase temporary buffer size js1304
2016-06-17 12:56 ` Vlastimil Babka
2016-06-17 7:57 ` [PATCH v3 6/9] mm/page_owner: use stackdepot to store stacktrace js1304
2016-10-26 13:06 ` [v3,6/9] " Sascha Silbe
2016-10-27 0:17 ` Joonsoo Kim
2016-12-22 23:37 ` Sascha Silbe
2016-06-17 7:57 ` [PATCH v3 7/9] mm/page_owner: avoid null pointer dereference js1304
2016-06-17 13:32 ` Vlastimil Babka
2016-06-24 20:19 ` Andrew Morton [this message]
2016-06-17 7:57 ` [PATCH v3 8/9] mm/page_alloc: introduce post allocation processing on page allocator js1304
2016-06-17 7:57 ` [PATCH v3 9/9] mm/page_isolation: clean up confused code js1304
2016-06-17 13:34 ` Vlastimil Babka
2016-06-24 23:19 ` [PATCH v3 0/9] reduce memory usage by page_owner Andrew Morton
2016-06-27 5:45 ` Joonsoo Kim
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