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Tue, 25 Feb 2020 14:46:30 +0000 (UTC) Received: from ovpn-117-227.ams2.redhat.com (ovpn-117-227.ams2.redhat.com [10.36.117.227]) by smtp.corp.redhat.com (Postfix) with ESMTP id 31CA75DA2C; Tue, 25 Feb 2020 14:46:24 +0000 (UTC) Message-ID: Subject: Re: BUG: unable to handle kernel NULL pointer dereference in cipso_v4_sock_setattr From: Paolo Abeni To: Dmitry Vyukov , Paul Moore Cc: syzbot , cpaasch@apple.com, David Miller , Davide Caratti , Florian Westphal , kuba@kernel.org, Alexey Kuznetsov , LKML , linux-security-module , matthieu.baerts@tessares.net, netdev , peter.krystad@linux.intel.com, syzkaller-bugs , Hideaki YOSHIFUJI Date: Tue, 25 Feb 2020 15:46:23 +0100 In-Reply-To: References: <000000000000a719a9059f62246e@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.5 (3.32.5-1.fc30) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 2020-02-25 at 15:27 +0100, Dmitry Vyukov wrote: > On Tue, Feb 25, 2020 at 3:20 PM Paul Moore wrote: > > On Tue, Feb 25, 2020 at 3:19 AM syzbot > > wrote: > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: ca7e1fd1 Merge tag 'linux-kselftest-5.6-rc3' of git://git... > > > git tree: upstream > > > console output: https://syzkaller.appspot.com/x/log.txt?x=179f0931e00000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a61f2164c515c07f > > > dashboard link: https://syzkaller.appspot.com/bug?extid=f4dfece964792d80b139 > > > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14fdfdede00000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17667de9e00000 > > > > > > The bug was bisected to: > > > > > > commit 2303f994b3e187091fd08148066688b08f837efc > > > Author: Peter Krystad > > > Date: Wed Jan 22 00:56:17 2020 +0000 > > > > > > mptcp: Associate MPTCP context with TCP socket > > > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14fbec81e00000 > > > final crash: https://syzkaller.appspot.com/x/report.txt?x=16fbec81e00000 > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12fbec81e00000 > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+f4dfece964792d80b139@syzkaller.appspotmail.com > > > Fixes: 2303f994b3e1 ("mptcp: Associate MPTCP context with TCP socket") > > > > > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > > > #PF: supervisor instruction fetch in kernel mode > > > #PF: error_code(0x0010) - not-present page > > > PGD 8e171067 P4D 8e171067 PUD 93fa2067 PMD 0 > > > Oops: 0010 [#1] PREEMPT SMP KASAN > > > CPU: 0 PID: 8984 Comm: syz-executor066 Not tainted 5.6.0-rc2-syzkaller #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > > RIP: 0010:0x0 > > > Code: Bad RIP value. > > > RSP: 0018:ffffc900020b7b80 EFLAGS: 00010246 > > > RAX: 1ffff110124ba600 RBX: 0000000000000000 RCX: ffff88809fefa600 > > > RDX: ffff8880994cdb18 RSI: 0000000000000000 RDI: ffff8880925d3140 > > > RBP: ffffc900020b7bd8 R08: ffffffff870225be R09: fffffbfff140652a > > > R10: fffffbfff140652a R11: 0000000000000000 R12: ffff8880925d35d0 > > > R13: ffff8880925d3140 R14: dffffc0000000000 R15: 1ffff110124ba6ba > > > FS: 0000000001a0b880(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffffffffffffffd6 CR3: 00000000a6d6f000 CR4: 00000000001406f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > cipso_v4_sock_setattr+0x34b/0x470 net/ipv4/cipso_ipv4.c:1888 > > > netlbl_sock_setattr+0x2a7/0x310 net/netlabel/netlabel_kapi.c:989 > > > smack_netlabel security/smack/smack_lsm.c:2425 [inline] > > > smack_inode_setsecurity+0x3da/0x4a0 security/smack/smack_lsm.c:2716 > > > security_inode_setsecurity+0xb2/0x140 security/security.c:1364 > > > __vfs_setxattr_noperm+0x16f/0x3e0 fs/xattr.c:197 > > > vfs_setxattr fs/xattr.c:224 [inline] > > > setxattr+0x335/0x430 fs/xattr.c:451 > > > __do_sys_fsetxattr fs/xattr.c:506 [inline] > > > __se_sys_fsetxattr+0x130/0x1b0 fs/xattr.c:495 > > > __x64_sys_fsetxattr+0xbf/0xd0 fs/xattr.c:495 > > > do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > Netdev folks, I'm not very familiar with the multipath TCP code so I > > was wondering if you might help me out a bit with this report. Based > > on the stack trace above it looks like for a given AF_INET sock "sk", > > inet_sk(sk)->is_icsk is true but inet_csk(sk) is NULL; should this be > > possible under normal conditions or is there an issue somewhere? > > Paolo has submitted some patch for testing for this bug, not sure if > you have seen it, just in case: > https://groups.google.com/forum/#!msg/syzkaller-bugs/dqwnTBh-MQw/LhgSZYGsBgAJ I sent the patch to the syzbot ML only, for testing before posting on netdev, so Paul likely have not seen it yet, sorry. @Dmitry: I did not get any reply yet from syzbot, are there any problems or is this the usual time-frame? Thank you! Paolo