** 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. The failing VM was running on a host with kernel 3.13.0-66-generic (trusty). Hosts' qemu version: 1:2.2+dfsg-5expubuntu9.3~cloud0. Hosts' seabios: 1.7.5-1ubuntu1~cloud0 The flavour of this VM is 4 CPUs, 8G RAM, 80G of root disk, 0 G swap and 0 G ephemeral disk. Here is the trace from KASAN (from the VM): The error message can be observed in the dmesg when the guest VM booted - with v3.13.0-65 with KASAN enabled. + with v3.13.0-65 with KASAN enabled and "slub_debug=PU,kmalloc-32" in + kernel command line. ================================================================== - BUG: KASan: use after free in blk_mq_register_disk+0x193/0x260 at addr ffff8801ec247400 + BUG: KASan: out of bounds access in blk_mq_register_disk+0x193/0x260 at addr ffff8801f43f4d90 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...... + INFO: Allocated in blk_mq_init_hw_queues+0x778/0x920 age=5 cpu=1 pid=1 + __slab_alloc+0x4f8/0x560 + __kmalloc_node+0xad/0x310 + blk_mq_init_hw_queues+0x778/0x920 + blk_mq_init_queue+0x5f7/0x6c0 + virtblk_probe+0x207/0x980 + virtio_dev_probe+0x1be/0x280 + driver_probe_device+0xe2/0x5c0 + __driver_attach+0xc3/0xd0 + bus_for_each_dev+0x95/0xe0 + driver_attach+0x2b/0x30 + bus_add_driver+0x268/0x360 + driver_register+0xd3/0x1a0 + register_virtio_driver+0x3c/0x60 + init+0x53/0x80 + do_one_initcall+0xda/0x1a0 + kernel_init_freeable+0x1eb/0x27e + INFO: Freed in kzfree+0x2d/0x40 age=13 cpu=0 pid=8 + __slab_free+0x2ab/0x3f0 + kfree+0x161/0x170 + kzfree+0x2d/0x40 + aa_free_task_context+0x5d/0xa0 + apparmor_cred_free+0x24/0x40 + security_cred_free+0x2b/0x30 + put_cred_rcu+0x38/0x140 + rcu_nocb_kthread+0x25a/0x410 + kthread+0x101/0x120 + ret_from_fork+0x58/0x90 + INFO: Slab 0xffffea0007d0fd00 objects=23 used=21 fp=0xffff8801f43f52d0 flags=0x2ffff0000004080 + INFO: Object 0xffff8801f43f4d70 @offset=3440 fp=0xffff8801f43f5830 + Bytes b4 ffff8801f43f4d60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ + Object ffff8801f43f4d70: 00 ac 61 f7 01 88 ff ff 00 ac 69 f7 01 88 ff ff ..a.......i..... + Object ffff8801f43f4d80: 00 ac 71 f7 01 88 ff ff 00 ac 79 f7 01 88 ff ff ..q.......y..... 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 + ffffea0007d0fd00 ffff8801f40cf9a8 ffffffff81a6ce35 ffff8801f7001c00 + ffff8801f40cf9d8 ffffffff81244aed ffff8801f7001c00 ffffea0007d0fd00 + ffff8801f43f4d70 ffff8801f779ac98 ffff8801f40cfa00 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 + [<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 + ffff8801f43f4c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc + ffff8801f43f4d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc 00 00 + >ffff8801f43f4d80: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc + ^ + ffff8801f43f4e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc + ffff8801f43f4e80: fc fc fc fc fc fc fc fc fc 00 00 00 00 fc fc fc ==================================================================
-- 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
