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[209.85.217.43]) by smtp.gmail.com with ESMTPSA id v79sm4728003vkv.13.2019.02.20.13.08.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Feb 2019 13:08:45 -0800 (PST) Received: by mail-vs1-f43.google.com with SMTP id n10so14854300vso.13 for ; Wed, 20 Feb 2019 13:08:44 -0800 (PST) X-Received: by 2002:a67:c00a:: with SMTP id v10mr20437112vsi.66.1550696924229; Wed, 20 Feb 2019 13:08:44 -0800 (PST) MIME-Version: 1.0 References: <20190220204058.11676-1-daniel.vetter@ffwll.ch> In-Reply-To: <20190220204058.11676-1-daniel.vetter@ffwll.ch> From: Kees Cook Date: Wed, 20 Feb 2019 13:08:30 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm: Don't let userspace spam allocations warnings To: Daniel Vetter Cc: DRI Development , LKML , Daniel Vetter , Andrew Morton , Mike Rapoport , Michal Hocko , Roman Gushchin , Vlastimil Babka , Jan Stancek , Andrey Ryabinin , "Michael S. Tsirkin" , Huang Ying , Bartosz Golaszewski , Linux-MM Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Feb 20, 2019 at 12:41 PM Daniel Vetter wrote: > > memdump_user usually gets fed unchecked userspace input. Blasting a > full backtrace into dmesg every time is a bit excessive - I'm not sure > on the kernel rule in general, but at least in drm we're trying not to > let unpriviledge userspace spam the logs freely. Definitely not entire > warning backtraces. > > It also means more filtering for our CI, because our testsuite > exercises these corner cases and so hits these a lot. > > Signed-off-by: Daniel Vetter Reviewed-by: Kees Cook -Kees > Cc: Andrew Morton > Cc: Mike Rapoport > Cc: Michal Hocko > Cc: Roman Gushchin > Cc: Vlastimil Babka > Cc: Jan Stancek > Cc: Kees Cook > Cc: Andrey Ryabinin > Cc: "Michael S. Tsirkin" > Cc: Huang Ying > Cc: Bartosz Golaszewski > Cc: linux-mm@kvack.org > --- > mm/util.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/util.c b/mm/util.c > index 1ea055138043..379319b1bcfd 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -150,7 +150,7 @@ void *memdup_user(const void __user *src, size_t len) > { > void *p; > > - p = kmalloc_track_caller(len, GFP_USER); > + p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN); > if (!p) > return ERR_PTR(-ENOMEM); > > -- > 2.20.1 > -- Kees Cook