Red Hat Bugzilla – Bug 436123
selinux corrupts ext3 fs
Last modified: 2009-01-09 01:06:43 EST
Description of problem: After running `yum update` which completed without error, and rebooting (because the kernel was upgraded), Fedora 8 would not start because the / partition (ext3) was found to have problems: "primary superblock differs from backup, check forced". e2fsck could not resolve the problems and dropped to a shell. Rather than run e2fsck on the mounted / partition, I booted from a live CD to run e2fsck. There were problems with the link count and directory detachment of several files, which were saved to "/lost+found". In all cases, the file contents were related to SELinux. I can send the contents of /lost+found if this would help. Version-Release number of selected component (if applicable): several selinux components updated - see attached yum.log How reproducible: Happened once (and once before on a Fedora 8 release candidate). Have not attempted to reproduce. It is possible that the fs corruption had occurred before the yum update, but I had the same experience twice and on both occasions the yum update was the last step before reboot. Additional info: I have used Red Hat Linux for 9 years, and only twice have I had an e2fsck failure that was not caused by faulty hardware. In both cases, selinux was implicated. After the first occasion (on a release candidate of Fedora 8), I disabled selinux when installing (on an empty partition) (the final) Fedora 8, and removed the selinux RPMs from my system as best I could, hoping that this would make me safe. This is a critical bug - the consequences on a remote system might include failure to restart after a software upgrade; or the danger of running an inconsistent filesystem. In 9 years this is the only serious bug I have ever found in a Red Hat product. No other software component has ever corrupted an ext3 fs, despite occasional crashes of desktop applications, power failures etc: ext3 is rock-solid and this is one reason why I love using Linux. I have to wonder why selinux, with no obvious crash or reported error, seems to be able to damage an ext3 filesystem. It would be useful to know how to permanently remove selinux so that the other (extremely well-engineered) parts of Fedora 8 can be used without it.
Created attachment 296885 [details] yum.log for the update that appeared to trigger the bug
So FWIW, it is unlikely that selinux is at fault; rather it may be ext3's extended attribute handling, which selinux makes use of... e2fsprogs-1.40.4 has some new checks in place that may have forced the check (the "primary superblock differs..." message; I wish it printed what the differences *were*) so it is quite possible that the problems occurred much earlier and were only found due to the forced check. When was the last time the fs was checked? Do you have either the repair output, or an e2image of the filesystem prior to repair, so we can get an idea of what corruption was found?
Created attachment 297043 [details] Contents of /lost+found after fsck
The fs was created in November 2007, and might not have been checked since then. Sorry, no repair output, no e2image, but I have attached the contents of /lost+found which might be some help.
I'll look at the lost+found contents after the fsck, but I'm not sure it will be a lot of help. Unfortunately this looks a bit like "something, somewhere went wrong at some point and e2fsck discovered it" but it's not a lot to go on. Regarding selinux, you can certainly disable it if you wish, but I don't think it's the root cause here.
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Fedora 8 changed to end-of-life (EOL) status on 2009-01-07. Fedora 8 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. Thank you for reporting this bug and we are sorry it could not be fixed.