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d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=x0DDJv++iHMwFovcTSUdqNPnf7WFz++klT2C8MF2YAk=; b=VTJJno78jCoUpeqbC8/RjT29JbTSHgoHubodkP5hX6vvMMLFsRzV8BunnYQrn7ejiZ 85JFvNNS3MIRv0715/Ucktc7XK5EKmHQH1t3aa7d0/oJiJDw528F/1YDO4ayI5Lwti0F 2b/vdCE5hyM0DTWl9A5TWqC72qy1ZJU/GqtQHiUBkxBVOS8bg8rAKzyAnY9Qm+0sgP+B d94sKua1+unGIa3OedhTJjdtKjCRy6KbWdAX9dDY9YpfEYKKQjg3hhegkR5CBV8z8iuL GsIvUU5qTxTDQdxG6SemJswCftfoD5+8MxlKKoWQvci7iY1iRjuYnoT4yzMAvOz8MO9J OaXg== X-Gm-Message-State: APjAAAUfLPe5iflT5ZDA+wNve+6l8xVYpsAlAYLeAfVMLrqFo68aJGZ0 TsKC//wRdj4q/yjLS0uQJNgmWAr6XxmjFhAXYfdK X-Google-Smtp-Source: APXvYqwWKX3jUx2E5vy+abrEsYm2bW9GwEripUqXhbnIh2aKLOWYSU7BVwy2dpskrNrYbYThDA/eBzwYY572UgTANug= X-Received: by 2002:a50:e108:: with SMTP id h8mr49416136edl.196.1582640455132; Tue, 25 Feb 2020 06:20:55 -0800 (PST) MIME-Version: 1.0 References: <000000000000a719a9059f62246e@google.com> In-Reply-To: <000000000000a719a9059f62246e@google.com> From: Paul Moore Date: Tue, 25 Feb 2020 09:20:44 -0500 Message-ID: Subject: Re: BUG: unable to handle kernel NULL pointer dereference in cipso_v4_sock_setattr To: syzbot Cc: cpaasch@apple.com, davem@davemloft.net, dcaratti@redhat.com, fw@strlen.de, kuba@kernel.org, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, matthieu.baerts@tessares.net, netdev@vger.kernel.org, pabeni@redhat.com, peter.krystad@linux.intel.com, syzkaller-bugs@googlegroups.com, yoshfuji@linux-ipv6.org Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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? -- paul moore www.paul-moore.com