Bugtraq mailing list archives
Re: [reiserfs-list] major security bug in reiserfs (may affect SuSE Linux)
From: "Vladimir V. Saveliev" <vs () NAMESYS BOTIK RU>
Date: Wed, 10 Jan 2001 03:56:32 +0300
Hi Marc Lehmann wrote:
We are still investigating, but there seems to be a major security problem in at least some versions of reiserfs. Since reiserfs is shipped with newer versions of SuSE Linux and the problem is too easy to reproduce and VERY dangerous I think alerting people to this problem is in order. We have tested and verified this problem on a number of different systems and kernels 2.2.17/2.2.8 with reiserfs-3.5.28 and probably other versions. Basically, you do: mkdir "$(perl -e 'print "x" x 768')" I.e. create a very long directory. The name doesn't seem to be of relevance (we found this out by doing mkdir "$(cat /etc/hosts)" for other tests). This works. The next ls (or echo *) command will segfault and the kernel oopses. all following accesses to the volume in question will oops and hang the process, even afetr a reboot.
Hmm, mkdir "$(perl -e 'print "x" x 768')" ls echo * works here as it should. (2.2.18 and reiserfs-3.5.29) Did I miss something? Thanks, vs
reiserfsck (the filesystem check program) does _NOT_ detect or solve this problem: Replaying journal..ok Checking S+tree..ok Comparing bitmaps..ok But fortunately, rmdir <filename> works and seems to leave the filesystem undamaged. Since a kernel oops results (see below), this indicates a buffer overrun (the kernel jumps to address 78787878, which is "xxxx") inside the kernel, which is of course very nasty (think ftp-upload!) and certainly gives you root access from anywhere, even from inside a chrooted environment. We didn't pursue this further. The best workaround at this time seems to be to uninstall reiserfs completely or not allow any user access (even indirect) to these volumes. While this individual bug might be easy to fix, we believe that other, similar bugs should be easy to find so reiserfs should not be trusted (it shouldn't be trusted to full user access for other reasons anyway, but it is still widely used). Unable to handle kernel paging request at virtual address 78787878 current->tss.cr3 = 0d074000, %cr3 = 0d074000 *pde = 00000000 Oops: 0002 CPU: 0 EIP: 0010:[<c013f875>] EFLAGS: 00010282 eax: 00000000 ebx: bfffe78c ecx: 00000000 edx: bfffe78c esi: ccbddd62 edi: 78787878 ebp: 00000300 esp: ccbddd3c ds: 0018 es: 0018 ss: 0018 Process bash (pid: 292, process nr: 54, stackpage=ccbdd000) Stack: c013f66a ccbddf6c cd100000 ccbddd62 0000030c c0136d49 00000700 00002013 00001000 7878030c 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 78787878 Call Trace: [<c013f66a>] [<c0136d49>] Code: 89 1f 8b 44 24 18 29 47 08 31 c0 5b 5e 5f 5d 81 c4 2c 01 00 -- -----==- | ----==-- _ | ---==---(_)__ __ ____ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / pcg () opengroup org |e| -=====/_/_//_/\_,_/ /_/\_\ XX11-RIPE --+ The choice of a GNU generation | |
Current thread:
- major security bug in reiserfs (may affect SuSE Linux) Marc Lehmann (Jan 09)
- Re: [reiserfs-list] major security bug in reiserfs (may affect SuSE Linux) John Morrison (Jan 09)
- Re: [reiserfs-list] major security bug in reiserfs (may affect SuSE Linux) Chris Mason (Jan 09)
- Re: [reiserfs-list] major security bug in reiserfs (may affect SuSE Linux) Vladimir V. Saveliev (Jan 09)
- Re: major security bug in reiserfs (may affect SuSE Linux) Andreas Ferber (Jan 10)
- Re: major security bug in reiserfs (may affect SuSE Linux) Mark Glines (Jan 12)
- Re: major security bug in reiserfs (may affect SuSE Linux) Jack Coates (Jan 12)
- Re: major security bug in reiserfs (may affect SuSE Linux) Gigi Sullivan (Jan 10)
- Re: major security bug in reiserfs (may affect SuSE Linux) Christian Zuckschwerdt (Jan 10)
- Re: major security bug in reiserfs (may affect SuSE Linux) Ryan Russell (Jan 10)
- Re: major security bug in reiserfs (may affect SuSE Linux) Christian Zuckschwerdt (Jan 10)
- Re: major security bug in reiserfs (may affect SuSE Linux) Felix von Leitner (Jan 12)
- Re: major security bug in reiserfs (may affect SuSE Linux) Ryan Russell (Jan 10)
- <Possible follow-ups>
- Re: major security bug in reiserfs (may affect SuSE Linux) Marc Lehmann (Jan 10)
- Re: major security bug in reiserfs (may affect SuSE Linux) Ben Greenbaum (Jan 10)
(Thread continues...)