Test on Xenial
Before:
Last login: Wed Aug 15 19:29:38 2018 from 192.168.122.1
$ uname -a
Linux bionic 4.4.0-133-generic #159-Ubuntu SMP Fri Aug 10 07:31:43 UTC 2018
x86_64 x86_64 x86_64 GNU/Linux
$ echo 9 | sudo tee /proc/sys/kernel/printk
9
$ sudo losetup --find --show --partscan rlv_grkgld.1mb
<hung>
[ 309.251832] partition (null) (21 pp's found) is not contiguous
[ 309.254557] partition (null) (2 pp's found) is not contiguous
[ 309.256893] partition (null) (1 pp's found) is not contiguous
...
[ 309.335870] partition (null) (2 pp's found) is not contiguous
[ 309.338133] partition (null) (64 pp's found) is not contiguous
[ 309.339719] partition (null) (1 pp's found) is not contiguous
[ 309.345218] BUG: unable to handle kernel paging request at 0000000000001040
[ 309.347776] IP: [<ffffffff8140bb29>] strnlen+0x9/0x40
[ 309.349813] PGD 0
[ 309.350719] Oops: 0000 [#1] SMP
[ 309.351987] Modules linked in: isofs kvm_intel kvm irqbypass input_leds
joydev serio_raw sch_fq_codel
ib_iser rdma_cm iw_cm ib_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp libiscsi_tcp
libiscsi scsi_transport_i
scsi ip_tables x_tables autofs4 btrfs raid10 raid456 async_raid6_recov
async_memcpy async_pq async_xor as
ync_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear psmouse floppy
[ 309.367248] CPU: 1 PID: 979 Comm: losetup Not tainted 4.4.0-133-generic
#159-Ubuntu
[ 309.369461] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.10.2-1ubuntu1 04/01/2014
[ 309.372403] task: ffff880039a78000 ti: ffff88003b2f0000 task.ti:
ffff88003b2f0000
[ 309.375267] RIP: 0010:[<ffffffff8140bb29>] [<ffffffff8140bb29>]
strnlen+0x9/0x40
[ 309.377806] RSP: 0018:ffff88003b2f3830 EFLAGS: 00010086
[ 309.379278] RAX: ffffffff81cd2b01 RBX: ffffffff8211eb6c RCX: 0000000000000000
[ 309.381360] RDX: 0000000000001040 RSI: ffffffffffffffff RDI: 0000000000001040
[ 309.384074] RBP: ffff88003b2f3830 R08: 000000000000ffff R09: 000000000000ffff
[ 309.385894] R10: ffff88003b2f39e8 R11: 0000000000000251 R12: 0000000000001040
[ 309.387906] R13: ffffffff8211ef40 R14: 00000000ffffffff R15: 0000000000000000
[ 309.389937] FS: 00007f7e0163c740(0000) GS:ffff88003fc80000(0000)
knlGS:0000000000000000
[ 309.392496] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 309.394040] CR2: 0000000000001040 CR3: 0000000039a48000 CR4: 0000000000000670
[ 309.396505] Stack:
[ 309.397306] ffff88003b2f3868 ffffffff8140d8cb ffffffff8211eb6c
ffffffff8211ef40
[ 309.400370] ffff88003b2f3980 ffffffff81d00816 ffffffff81d00816
ffff88003b2f38d8
[ 309.403210] ffffffff8140f385 0000000000000092 0000000000000092
000000000000000c
[ 309.406231] Call Trace:
[ 309.407114] [<ffffffff8140d8cb>] string.isra.4+0x3b/0xd0
[ 309.408818] [<ffffffff8140f385>] vsnprintf+0x135/0x530
[ 309.410869] [<ffffffff8140f78d>] vscnprintf+0xd/0x30
[ 309.412283] [<ffffffff810dd5e3>] vprintk_emit+0x123/0x520
[ 309.413983] [<ffffffff810ddb69>] vprintk_default+0x29/0x40
[ 309.415495] [<ffffffff811933c0>] printk+0x5a/0x76
[ 309.417463] [<ffffffff813e9571>] aix_partition+0x5d1/0x600
[ 309.419595] [<ffffffff811956ad>] ? pagecache_get_page+0x2d/0x1c0
[ 309.421218] [<ffffffff813ecefb>] msdos_partition+0x86b/0x880
[ 309.423173] [<ffffffff81252ef0>] ? blkdev_readpages+0x20/0x20
[ 309.424963] [<ffffffff81195a39>] ? read_cache_page+0x19/0x20
[ 309.426515] [<ffffffff813e6ced>] ? read_dev_sector+0x2d/0x90
[ 309.428280] [<ffffffff8140f819>] ? snprintf+0x49/0x60
[ 309.429707] [<ffffffff813ec690>] ? parse_solaris_x86+0x210/0x210
[ 309.432081] [<ffffffff813e80d0>] check_partition+0x140/0x220
[ 309.433845] [<ffffffff813e75cb>] rescan_partitions+0xbb/0x2b0
[ 309.435421] [<ffffffff8135118e>] ? security_capable+0x4e/0x70
[ 309.437006] [<ffffffff813e2545>] __blkdev_reread_part+0x65/0x70
[ 309.438598] [<ffffffff813e2573>] blkdev_reread_part+0x23/0x40
[ 309.440173] [<ffffffff81591a98>] loop_reread_partitions+0x28/0x50
[ 309.442811] [<ffffffff81591e5a>] loop_set_status+0x39a/0x3d0
[ 309.444381] [<ffffffff81592150>] loop_set_status64+0x50/0x70
[ 309.446146] [<ffffffff815934d1>] lo_ioctl+0xf1/0x8b0
[ 309.447547] [<ffffffff813e2dde>] blkdev_ioctl+0x25e/0x910
[ 309.449056] [<ffffffff81235663>] ? __fd_install+0x33/0xe0
[ 309.451395] [<ffffffff81253a7d>] block_ioctl+0x3d/0x50
[ 309.453275] [<ffffffff8122aaff>] do_vfs_ioctl+0x2af/0x4b0
[ 309.455019] [<ffffffff812267e4>] ? putname+0x54/0x60
[ 309.456434] [<ffffffff81215d0f>] ? do_sys_open+0x1bf/0x2a0
[ 309.457943] [<ffffffff8122ad79>] SyS_ioctl+0x79/0x90
[ 309.459886] [<ffffffff8185424e>] entry_SYSCALL_64_fastpath+0x22/0xc1
[ 309.462722] Code: 00 00 80 3f 00 55 48 89 e5 74 11 48 89 f8 48 83 c0 01 80
38 00 75 f7 48 29 f8 5d c3
31 c0 5d c3 66 90 55 48 85 f6 48 89 e5 74 2e <80> 3f 00 74 29 48 8d 57 01 48 8d
04 37 eb 0d 48 8d 4a 01 8
0 79
[ 309.475971] RIP [<ffffffff8140bb29>] strnlen+0x9/0x40
[ 309.477537] RSP <ffff88003b2f3830>
[ 309.478624] CR2: 0000000000001040
[ 309.479703] ---[ end trace 4fe99281b613609c ]---
After:
$ uname -a
Linux bionic 4.4.0-133-generic #159+sf181954.1 SMP Wed Aug 15 14:18:05 -03 2018
x86_64 x86_64 x86_64 GNU/Linux
$ echo 9 | sudo tee /proc/sys/kernel/printk
9
$ sudo losetup --find --show --partscan rlv_grkgld.1mb
/dev/loop0
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https://bugs.launchpad.net/bugs/1787281
Title:
errors when scanning partition table of corrupted AIX disk
Status in linux package in Ubuntu:
Incomplete
Bug description:
[Impact]
* Users with disks/LUNs used for AIX operating system installations
previously, which possibly undergone overwrites/corruption on the
partition table, might hit kernel failures during partition scan
of such disk/LUN, and possibly hang the system (seen with retries).
* The Linux kernel should be robust to corrupted disk data, performing
a better sanitization/checks and not failing.
* The fix are a couple of simple logic changes to make the code
of the AIX partition table parser more robust.
[Test Case]
* Run the partition scan on the (trimmed) disk image of the AIX lun.
(It's not provided here since it contains customer data), with this
command:
$ sudo losetup --find --show --partscan rlv_grkgld.1mb
* On failure, the command hangs, and messages like these are printed
to the console, depending on the kernel version (see tests below)
[ 270.506420] partition (null) (3 pp's found) is not contiguous
[ 270.597428] BUG: unable to handle kernel paging request at
0000000000001000
[ 270.599525] IP: [<ffffffff81379d4d>] strnlen+0xd/0x40
* On success, the command prints a loop device name, for example:
/dev/loop0
[Regression Potential]
* Low. Both changes are simple improvements in logic.
* This affects users which mount disks/LUNs from the AIX OS;
it should only change behavior for users which relied on a
uninitialized variables to work correctly during partition
scan of those disks/LUNs which should be rare as the code
is likely to fail as we observe in this scenario.
* This has been tested on Cosmic, Bionic, Xenial, and Trusty.
[Other Info]
* Patches will be sent to the kernel-team mailing list.
Bug Description:
---------------
We've recently received a disk image from an AIX LUN that when
attached on Linux displayed errors on console, then eventually
hung the system (specially if the SCSI bus was re-scanned, and
leading to another partition scan).
Apparently the LUN was originally installed with AIX and later
exercised with some I/O stress/overwrites which caused certain
bits to be wrong in just the right way for Linux to get a NULL
pointer and invalid data.
This is the test-case used ('--partscan' is the important bit).
$ sudo losetup --show --find --partscan aix-lun.img
Since the original code is old, it affects several releases.
It's interesting to fix this on 14.04 and up, on which IBM
Power servers were initially supported (since they can run
AIX too, and possibly hit this due to an already used disk/LUN).
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1787281/+subscriptions
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