This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed- eoan' to 'verification-done-eoan'. If the problem still exists, change the tag 'verification-needed-eoan' to 'verification-failed-eoan'.
If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: verification-needed-eoan -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1862114 Title: pty03 from pty in ubuntu_ltp failed on Eoan Status in ubuntu-kernel-tests: In Progress Status in linux package in Ubuntu: In Progress Status in linux source package in Xenial: Fix Committed Status in linux source package in Bionic: Fix Committed Status in linux source package in Disco: Fix Committed Status in linux source package in Eoan: Fix Committed Bug description: == 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. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-kernel-tests/+bug/1862114/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
