From mboxrd@z Thu Jan 1 00:00:00 1970 From: syzbot Subject: KASAN: use-after-free Read in bpf_csum_update Date: Sun, 03 Jun 2018 16:36:03 -0700 Message-ID: <000000000000bec587056dc547ba@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes To: ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: bcece5dc40b9 bpf: Change bpf_fib_lookup to return -EAFNOSU.. git tree: bpf-next console output: https://syzkaller.appspot.com/x/log.txt?x=161e2c6f800000 kernel config: https://syzkaller.appspot.com/x/.config?x=e4078980b886800c dashboard link: https://syzkaller.appspot.com/bug?extid=3d0b2441dbb71751615e compiler: gcc (GCC) 8.0.1 20180413 (experimental) syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=17cb5adf800000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17ebf19f800000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+3d0b2441dbb71751615e@syzkaller.appspotmail.com random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) ================================================================== BUG: KASAN: use-after-free in ____bpf_csum_update net/core/filter.c:1907 [inline] BUG: KASAN: use-after-free in bpf_csum_update+0xb4/0xc0 net/core/filter.c:1901 Read of size 1 at addr ffff8801ad062f10 by task syz-executor354/4488 CPU: 1 PID: 4488 Comm: syz-executor354 Not tainted 4.17.0-rc6+ #29 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 ____bpf_csum_update net/core/filter.c:1907 [inline] bpf_csum_update+0xb4/0xc0 net/core/filter.c:1901 The buggy address belongs to the page: page:ffffea0006b41880 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x2fffc0000000000() raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff raw: ffffea0006b41820 ffffea0006b671a0 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801ad062e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8801ad062e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff8801ad062f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8801ad062f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8801ad063000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== --- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches