** Description changed: + We are trying to debug the kernel using KASAN and we found that when a + VM is booting in our cloud, on the virtualised kernel, there is a use- + after-free access that should not be there. + + Here is the trace from KASAN: + The error message can be observed in the dmesg when the guest VM booted with v3.13.0-65 with KASAN enabled. ================================================================== BUG: KASan: use after free in blk_mq_register_disk+0x193/0x260 at addr ffff8801ec247400 Read of size 8 by task swapper/0/1 ============================================================================= BUG kmalloc-32 (Not tainted): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Slab 0xffffea0007b091c0 objects=128 used=128 fp=0x (null) flags=0x2ffff0000000080 INFO: Object 0xffff8801ec247400 @offset=1024 fp=0xffff8801ec247420 Bytes b4 ffff8801ec2473f0: 00 ac 71 ef 01 88 ff ff 00 ac 79 ef 01 88 ff ff ..q.......y..... Object ffff8801ec247400: 20 74 24 ec 01 88 ff ff 2f 76 69 72 74 75 61 6c t$...../virtual Object ffff8801ec247410: 2f 62 64 69 2f 32 35 33 3a 30 00 00 00 00 00 00 /bdi/253:0...... CPU: 0 PID: 1 Comm: swapper/0 Tainted: G B 3.13.0-65-generic #105 Hardware name: OpenStack Foundation OpenStack Nova, BIOS 1.7.5-20150310_111955-batsu 04/01/2014 ffffea0007b091c0 ffff8801ec0cb9a8 ffffffff81a6ce35 ffff8801ef001c00 ffff8801ec0cb9d8 ffffffff81244aed ffff8801ef001c00 ffffea0007b091c0 ffff8801ec247400 ffff8801ef79ac98 ffff8801ec0cba00 ffffffff8124ac36 Call Trace: [<ffffffff81a6ce35>] dump_stack+0x45/0x56 [<ffffffff81244aed>] print_trailer+0xfd/0x170 [<ffffffff8124ac36>] object_err+0x36/0x40 [<ffffffff8124cbf9>] kasan_report_error+0x1e9/0x3a0 [<ffffffff81319427>] ? sysfs_get+0x17/0x50 [<ffffffff814dee6b>] ? kobject_add_internal+0x29b/0x4a0 [<ffffffff8124d260>] kasan_report+0x40/0x50 [<ffffffff81696f00>] ? dev_printk_emit+0x20/0x40 [<ffffffff814ae7c3>] ? blk_mq_register_disk+0x193/0x260 [<ffffffff8124bee9>] __asan_load8+0x69/0xa0 [<ffffffff814ae7c3>] blk_mq_register_disk+0x193/0x260 [<ffffffff814a1572>] blk_register_queue+0xd2/0x170 [<ffffffff814b24cf>] add_disk+0x31f/0x720 [<ffffffff816ced9a>] virtblk_probe+0x58a/0x980 [<ffffffff816cd4c0>] ? virtblk_restore+0x100/0x100 [<ffffffff81601b8e>] virtio_dev_probe+0x1be/0x280 [<ffffffff8169d620>] ? __device_attach+0x70/0x70 [<ffffffff8169d0d2>] driver_probe_device+0xe2/0x5c0 [<ffffffff8169d620>] ? __device_attach+0x70/0x70 [<ffffffff8169d6e3>] __driver_attach+0xc3/0xd0 [<ffffffff8169a355>] bus_for_each_dev+0x95/0xe0 [<ffffffff8169c89b>] driver_attach+0x2b/0x30 [<ffffffff8169c298>] bus_add_driver+0x268/0x360 [<ffffffff8169dfe3>] driver_register+0xd3/0x1a0 [<ffffffff8218e4b9>] ? loop_init+0x14b/0x14b [<ffffffff8160213c>] register_virtio_driver+0x3c/0x60 [<ffffffff8218e50c>] init+0x53/0x80 [<ffffffff8100212a>] do_one_initcall+0xda/0x1a0 [<ffffffff8213816b>] kernel_init_freeable+0x1eb/0x27e [<ffffffff81a5bcd0>] ? rest_init+0x80/0x80 [<ffffffff81a5bcde>] kernel_init+0xe/0x130 [<ffffffff81a83028>] ret_from_fork+0x58/0x90 [<ffffffff81a5bcd0>] ? rest_init+0x80/0x80 Memory state around the buggy address: ffff8801ec247300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8801ec247380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8801ec247400: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff8801ec247480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801ec247500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================
** Tags added: sts -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1534054 Title: use-after-free found by KASAN in blk_mq_register_disk To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1534054/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
