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[2003:cb:c706:7900:b84d:7f2e:b638:3092]) by smtp.gmail.com with ESMTPSA id k6-20020adfb346000000b0027cb20605e3sm2470036wrd.105.2023.02.03.09.14.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Feb 2023 09:14:30 -0800 (PST) Message-ID: <753c53d3-84a6-da73-4121-0db4a71e4fde@redhat.com> Date: Fri, 3 Feb 2023 18:14:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v3 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock To: Wupeng Ma , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kuleshovmail@gmail.com, aneesh.kumar@linux.ibm.com References: <20230128063229.989058-1-mawupeng1@huawei.com> <20230128063229.989058-2-mawupeng1@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230128063229.989058-2-mawupeng1@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 7D1A2A0008 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: w8mpjbdyt8kbiz4ajp6t8jk8z3jobhn4 X-HE-Tag: 1675444474-779959 X-HE-Meta: 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 iwBTTUro oFVvSbPHbFw7naIYcVm39xBVYC2ywwky0K4owtlrvr6+SGlSi9OlyZSAS8USXVVSBjouvnaTJQ2eGstDDPVaDH5egatCMz+ckIcTExBB40+iWtjJh3aoI6SxJJJEri9Fok7GICI0SbC185LrASW8T/N32Bs1+l2vWHXlz4fwdKqHlBqBLpyqNAeSRbtDDmwgbtG4VXak7fR7+LQQdytm4TIRj/CihfjHdF/noyRTEFfcDshFHC8SY+fCO9LIcIk+4nqXQU5vMQMBoT2zahBvCWyqowDhU/P1I958BtK/hsfMP0UvX+7GRLEMLA5MRiZYJTObSqMngg42WxDMR9B/e5sWQ0gpqGzWTsgrjrmbXafRSPFFy3BmvR2LBJA9ZA06oFKO2wDtMaRzmeUw6opJTn0tFphciK+sfHK5qnGul8RXiLf4= 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 28.01.23 07:32, Wupeng Ma wrote: > From: Ma Wupeng > > While testing mlock, we have a problem if the len of mlock is ULONG_MAX. > The return value of mlock is zero. But nothing will be locked since the > len in do_mlock overflows to zero due to the following code in mlock: > > len = PAGE_ALIGN(len + (offset_in_page(start))); > > The same problem happens in munlock. > > Add new check and return -EINVAL to fix this overflowing scenarios since > they are absolutely wrong. > > Return 0 early to avoid burn a bunch of cpu cycles if len == 0. > > Signed-off-by: Ma Wupeng > --- > mm/mlock.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/mm/mlock.c b/mm/mlock.c > index 7032f6dd0ce1..eb09968ba27f 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -478,8 +478,6 @@ static int apply_vma_lock_flags(unsigned long start, size_t len, > end = start + len; > if (end < start) > return -EINVAL; > - if (end == start) > - return 0; > vma = mas_walk(&mas); > if (!vma) > return -ENOMEM; > @@ -575,7 +573,13 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla > if (!can_do_mlock()) > return -EPERM; > > + if (!len) > + return 0; > + > len = PAGE_ALIGN(len + (offset_in_page(start))); > + if (!len) > + return -EINVAL; > + > start &= PAGE_MASK; The "ordinary" overflows are detected in apply_vma_lock_flags(), correct? -- Thanks, David / dhildenb