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Fri, 6 Aug 2021 17:22:03 +0000 Subject: Re: [net-next:master 2/15] net/unix/af_unix.c:2471 manage_oob() warn: returning freed memory 'skb' To: Dan Carpenter , kbuild@lists.01.org Cc: lkp@intel.com, kbuild-all@lists.01.org, netdev@vger.kernel.org References: <202108051610.IrlkPw7d-lkp@intel.com> From: Shoaib Rao Message-ID: Date: Fri, 6 Aug 2021 10:22:00 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 In-Reply-To: <202108051610.IrlkPw7d-lkp@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: SN1PR12CA0095.namprd12.prod.outlook.com (2603:10b6:802:21::30) To SJ0PR10MB4494.namprd10.prod.outlook.com (2603:10b6:a03:2d4::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2606:b400:400:7444:8000::7bc] (2606:b400:8301:1010::16aa) by SN1PR12CA0095.namprd12.prod.outlook.com (2603:10b6:802:21::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4394.15 via Frontend Transport; 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In this case skb will not be freed. I used consume_skb as that is what the code uses. Shoaib. On 8/5/21 4:57 AM, Dan Carpenter wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master > head: c2eecaa193ff1e516a1b389637169ae86a6fa867 > commit: 314001f0bf927015e459c9d387d62a231fe93af3 [2/15] af_unix: Add OOB support > config: nios2-randconfig-m031-20210804 (attached as .config) > compiler: nios2-linux-gcc (GCC) 10.3.0 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot > Reported-by: Dan Carpenter > > New smatch warnings: > net/unix/af_unix.c:2471 manage_oob() warn: returning freed memory 'skb' > > vim +/skb +2471 net/unix/af_unix.c > > 314001f0bf9270 Rao Shoaib 2021-08-01 2446 static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, > 314001f0bf9270 Rao Shoaib 2021-08-01 2447 int flags, int copied) > 314001f0bf9270 Rao Shoaib 2021-08-01 2448 { > 314001f0bf9270 Rao Shoaib 2021-08-01 2449 struct unix_sock *u = unix_sk(sk); > 314001f0bf9270 Rao Shoaib 2021-08-01 2450 > 314001f0bf9270 Rao Shoaib 2021-08-01 2451 if (!unix_skb_len(skb) && !(flags & MSG_PEEK)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2452 skb_unlink(skb, &sk->sk_receive_queue); > 314001f0bf9270 Rao Shoaib 2021-08-01 2453 consume_skb(skb); > 314001f0bf9270 Rao Shoaib 2021-08-01 2454 skb = NULL; > 314001f0bf9270 Rao Shoaib 2021-08-01 2455 } else { > 314001f0bf9270 Rao Shoaib 2021-08-01 2456 if (skb == u->oob_skb) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2457 if (copied) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2458 skb = NULL; > 314001f0bf9270 Rao Shoaib 2021-08-01 2459 } else if (sock_flag(sk, SOCK_URGINLINE)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2460 if (!(flags & MSG_PEEK)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2461 u->oob_skb = NULL; > 314001f0bf9270 Rao Shoaib 2021-08-01 2462 consume_skb(skb); > > Need to set "skb = NULL;" after the consume. > > 314001f0bf9270 Rao Shoaib 2021-08-01 2463 } > 314001f0bf9270 Rao Shoaib 2021-08-01 2464 } else if (!(flags & MSG_PEEK)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2465 skb_unlink(skb, &sk->sk_receive_queue); > 314001f0bf9270 Rao Shoaib 2021-08-01 2466 consume_skb(skb); > 314001f0bf9270 Rao Shoaib 2021-08-01 2467 skb = skb_peek(&sk->sk_receive_queue); > 314001f0bf9270 Rao Shoaib 2021-08-01 2468 } > 314001f0bf9270 Rao Shoaib 2021-08-01 2469 } > 314001f0bf9270 Rao Shoaib 2021-08-01 2470 } > 314001f0bf9270 Rao Shoaib 2021-08-01 @2471 return skb; > 314001f0bf9270 Rao Shoaib 2021-08-01 2472 } > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org > From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============6590733416241124515==" MIME-Version: 1.0 From: Shoaib Rao To: kbuild-all@lists.01.org Subject: Re: [net-next:master 2/15] net/unix/af_unix.c:2471 manage_oob() warn: returning freed memory 'skb' Date: Fri, 06 Aug 2021 10:22:00 -0700 Message-ID: In-Reply-To: <202108051610.IrlkPw7d-lkp@intel.com> List-Id: --===============6590733416241124515== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable This is a false positive. consume_skb does necessarily frees the skb, it = decrements the refcnt abd if no reference exists frees the skb. In this = case skb will not be freed. I used consume_skb as that is what the code = uses. Shoaib. On 8/5/21 4:57 AM, Dan Carpenter wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.gi= t master > head: c2eecaa193ff1e516a1b389637169ae86a6fa867 > commit: 314001f0bf927015e459c9d387d62a231fe93af3 [2/15] af_unix: Add OOB = support > config: nios2-randconfig-m031-20210804 (attached as .config) > compiler: nios2-linux-gcc (GCC) 10.3.0 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot > Reported-by: Dan Carpenter > > New smatch warnings: > net/unix/af_unix.c:2471 manage_oob() warn: returning freed memory 'skb' > > vim +/skb +2471 net/unix/af_unix.c > > 314001f0bf9270 Rao Shoaib 2021-08-01 2446 static struct sk_buff *manage= _oob(struct sk_buff *skb, struct sock *sk, > 314001f0bf9270 Rao Shoaib 2021-08-01 2447 int flags, int copied) > 314001f0bf9270 Rao Shoaib 2021-08-01 2448 { > 314001f0bf9270 Rao Shoaib 2021-08-01 2449 struct unix_sock *u =3D unix= _sk(sk); > 314001f0bf9270 Rao Shoaib 2021-08-01 2450 > 314001f0bf9270 Rao Shoaib 2021-08-01 2451 if (!unix_skb_len(skb) && !(= flags & MSG_PEEK)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2452 skb_unlink(skb, &sk->sk_rec= eive_queue); > 314001f0bf9270 Rao Shoaib 2021-08-01 2453 consume_skb(skb); > 314001f0bf9270 Rao Shoaib 2021-08-01 2454 skb =3D NULL; > 314001f0bf9270 Rao Shoaib 2021-08-01 2455 } else { > 314001f0bf9270 Rao Shoaib 2021-08-01 2456 if (skb =3D=3D u->oob_skb) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2457 if (copied) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2458 skb =3D NULL; > 314001f0bf9270 Rao Shoaib 2021-08-01 2459 } else if (sock_flag(sk, S= OCK_URGINLINE)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2460 if (!(flags & MSG_PEEK)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2461 u->oob_skb =3D NULL; > 314001f0bf9270 Rao Shoaib 2021-08-01 2462 consume_skb(skb); > > Need to set "skb =3D NULL;" after the consume. > > 314001f0bf9270 Rao Shoaib 2021-08-01 2463 } > 314001f0bf9270 Rao Shoaib 2021-08-01 2464 } else if (!(flags & MSG_P= EEK)) { > 314001f0bf9270 Rao Shoaib 2021-08-01 2465 skb_unlink(skb, &sk->sk_r= eceive_queue); > 314001f0bf9270 Rao Shoaib 2021-08-01 2466 consume_skb(skb); > 314001f0bf9270 Rao Shoaib 2021-08-01 2467 skb =3D skb_peek(&sk->sk_= receive_queue); > 314001f0bf9270 Rao Shoaib 2021-08-01 2468 } > 314001f0bf9270 Rao Shoaib 2021-08-01 2469 } > 314001f0bf9270 Rao Shoaib 2021-08-01 2470 } > 314001f0bf9270 Rao Shoaib 2021-08-01 @2471 return skb; > 314001f0bf9270 Rao Shoaib 2021-08-01 2472 } > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org > --===============6590733416241124515==--