systemd-udevd crashes system with manipulated DOS partition table

Bug #1579336 reported by sqall on 2016-05-07
This bug affects 1 person
Affects Status Importance Assigned to Milestone
systemd (Ubuntu)

Bug Description

I wanted to test how operating systems react if the DOS partition table of a storage medium was manipulated. I created a DOS partition table with a few extended partitions. Because extended partitions are constructed like a linked list, I linked the "NEXT" field of the last extended partition to the first extended partition. This way, I created a loop in the partition table. Tools like fdisk detect that something is fishy in this partition table and output an error message. To test how operating systems react to it, I copied this image to an USB storage device and plugged it to my computer.

The systemd/udev process that handles this device seems to not check the DOS partition table for sanity. The process "/lib/systemd/systemd-udevd --daemon" completely uses all CPU time and all available memory. This crashes the system. Sometimes, it is able to recover by killing the process, but not every time.

I attached a screenshot (a real screenshot with a camera, because the system does not react anymore ;) ) of htop to show what the system does.



ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: udev 204-5ubuntu20.19
ProcVersionSignature: Ubuntu 3.13.0-85.129-generic 3.13.11-ckt36
Uname: Linux 3.13.0-85-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CurrentDesktop: XFCE
CustomUdevRuleFiles: 99-usb-disks.rules
Date: Sat May 7 10:43:21 2016
InstallationDate: Installed on 2014-11-12 (541 days ago)
InstallationMedia: Xubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140723)
MachineType: Hewlett-Packard HP EliteBook 8460p
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-85-generic root=/dev/mapper/xubuntu--vg-root ro
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install) 12/22/2011
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 68SCF Ver. F.22 161C
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 97.4A
dmi.chassis.asset.tag: CZC2033ZHD
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr68SCFVer.F.22:bd12/22/2011:svnHewlett-Packard:pnHPEliteBook8460p:pvrA0000C02:rvnHewlett-Packard:rn161C:rvrKBCVersion97.4A:cvnHewlett-Packard:ct10:cvr: HP EliteBook 8460p
dmi.product.version: A0000C02
dmi.sys.vendor: Hewlett-Packard

sqall (ubuntu-one-sqall) wrote :
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