oss-sec mailing list archives
Re: CVE request: Linux kernel DoS with syscall auditing
From: Andy Lutomirski <luto () amacapital net>
Date: Wed, 28 May 2014 18:31:56 -0700
On Wed, May 28, 2014 at 6:06 PM, Steve Grubb <sgrubb () redhat com> wrote:
On Wednesday, May 28, 2014 02:45:59 PM Andy Lutomirski wrote:Issuing a system call with a random large number will OOPS, depending on configuration. A configuration that will enable this bug is: # auditctl -a exit,always -S open No privilege whatsoever is required to trigger the OOPS.Do you have more information about this? I don't get an oops and I run with the audit system on all the time.
It's on lkml -- see: http://thread.gmane.org/gmane.linux.kernel/1713178/focus=1713179 http://thread.gmane.org/gmane.linux.kernel/1712799/focus=1713161 You need to pass a fairly large bogus syscall number. The auditsc code is completely missing any bounds checking on the syscall numbers.
It's possible that this can be extended to more than just a DoS -- with some care and willingness to exploit timing attacks, this is a read of arbitrary single bits in kernel memory.What platform? Where do the arbitrary bits go? What syscall are we talking about?
The audit system decides whether to log a syscall depending on a bit in the audit_krule mask. Since the mask read isn't bounds-checked, the caller can force it to read any bit, relative to the audit_krule. Anything that can tell the attacker the outcome of the filter decision will reveal the value of that bit.
There is a linux-audit mail list which seems to not have any emails about this problem. That is really the best place to discuss any issues with this subsystem and get it fixed.
There's already a patch on lkml. I'll cc linux-audit for the v2 patches. --Andy
Current thread:
- CVE request: Linux kernel DoS with syscall auditing Andy Lutomirski (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Greg KH (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Andy Lutomirski (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Greg KH (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Andy Lutomirski (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Andy Lutomirski (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Greg KH (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Steve Grubb (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing Andy Lutomirski (May 28)
- Re: CVE request: Linux kernel DoS with syscall auditing cve-assign (May 29)
- Re: Re: CVE request: Linux kernel DoS with syscall auditing Steve Grubb (May 29)
- Re: CVE request: Linux kernel DoS with syscall auditing P J P (May 29)