https://lists.ubuntu.com/archives/kernel-team/2020-February/107284.html
** Description changed: + == Justification == + The test case pty03 from pty in ubuntu_ltp is failing with kernel NULL + pointer dereference: + + [ 951.306823] BUG: kernel NULL pointer dereference, address: 0000000000000020 + [ 951.309960] #PF: supervisor write access in kernel mode + [ 951.312130] #PF: error_code(0x0002) - not-present page + [ 951.314227] PGD 0 P4D 0 + [ 951.315278] Oops: 0002 [#1] SMP PTI + [ 951.316705] CPU: 1 PID: 39102 Comm: pty03 Not tainted 5.4.0-12-generic #15-Ubuntu + [ 951.319737] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 + [ 951.322713] RIP: 0010:queue_work_on+0x1b/0x50 + + [ 951.352494] Call Trace: + [ 951.353244] slip_write_wakeup+0x25/0x30 [slip] + [ 951.354600] tty_wakeup+0x5b/0x70 + [ 951.355539] pty_unthrottle+0x19/0x30 + [ 951.356560] tty_unthrottle+0x42/0x60 + [ 951.357566] __tty_perform_flush+0x87/0x90 + [ 951.358768] n_tty_ioctl_helper+0xcc/0x150 + [ 951.359955] n_tty_ioctl+0x2d/0x100 + [ 951.360930] tty_ioctl+0x3c0/0x8e0 + [ 951.361882] ? __switch_to_asm+0x34/0x70 + [ 951.363049] ? __switch_to_asm+0x40/0x70 + [ 951.364191] ? __switch_to_asm+0x34/0x70 + [ 951.365261] ? __switch_to_asm+0x40/0x70 + [ 951.366382] ? __switch_to_asm+0x34/0x70 + [ 951.367452] ? __switch_to_asm+0x40/0x70 + [ 951.368523] ? __switch_to_asm+0x34/0x70 + [ 951.369693] ? __switch_to_asm+0x40/0x70 + [ 951.370829] ? __switch_to_asm+0x34/0x70 + [ 951.371923] ? __switch_to_asm+0x40/0x70 + [ 951.372998] ? __switch_to_asm+0x34/0x70 + [ 951.374097] ? __switch_to_asm+0x40/0x70 + [ 951.375183] ? __switch_to_asm+0x34/0x70 + [ 951.376288] ? __switch_to_asm+0x40/0x70 + [ 951.377390] ? __switch_to+0x110/0x470 + [ 951.378863] do_vfs_ioctl+0x407/0x670 + [ 951.380269] ? __schedule+0x2eb/0x740 + [ 951.381761] ksys_ioctl+0x67/0x90 + [ 951.383076] __x64_sys_ioctl+0x1a/0x20 + [ 951.384510] do_syscall_64+0x57/0x190 + [ 951.385896] entry_SYSCALL_64_after_hwframe+0x44/0xa9 + + == Fixes == + Indicated by the test case, this issue can be fixed by: + * 0ace17d5 (can, slip: Protect tty->disc_data in write_wakeup and + close with RCU) + + This patch can be cherry-picked into all of our kernels. + + == Test == + Test kernels could be found here: + https://people.canonical.com/~phlin/kernel/lp-1862114-pty03/ + + Tested on KVM nodes and the patched kernels work as expected, there + will be no more kernel null pointer dereference issue, and the test + can finish properly. + + == Regression potential == + Low, changes limited to two specific drivers for serial line TTY. This + issue can be reproduced quite easily and the patched kernels show + positive results. + + + == Original Bug Report == startup='Thu Feb 6 02:45:23 2020' tst_test.c:1215: INFO: Timeout per run is 0h 05m 00s pty03.c:101: INFO: Creating PTY with SLIP line discipline Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Test timeouted, sending SIGKILL! Cannot kill test processes! Congratulation, likely test hit a kernel bug. Exitting uncleanly... tag=pty03 stime=1580957123 dur=350 exit=exited stat=1 core=no cu=0 cs=0 This is a new test case, so it's not a regression. ** Changed in: linux (Ubuntu) Status: Confirmed => In Progress ** Changed in: linux (Ubuntu) Assignee: (unassigned) => Po-Hsu Lin (cypressyew) ** Changed in: linux (Ubuntu Eoan) Assignee: (unassigned) => Po-Hsu Lin (cypressyew) ** Changed in: linux (Ubuntu Disco) Assignee: (unassigned) => Po-Hsu Lin (cypressyew) ** Changed in: linux (Ubuntu Xenial) Assignee: (unassigned) => Po-Hsu Lin (cypressyew) ** Changed in: linux (Ubuntu Xenial) Status: Confirmed => In Progress ** Changed in: linux (Ubuntu Disco) Status: New => In Progress ** Changed in: linux (Ubuntu Eoan) Status: Confirmed => In Progress -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1862114 Title: pty03 from pty in ubuntu_ltp failed on Eoan To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-kernel-tests/+bug/1862114/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
