A flaw was found in the way the Linux kernel's perf subsystem retrieved userlevel stack traces on PowerPC systems. A local, unprivileged user could use this flaw to cause a denial of service on the system by creating a special stack layout that would force the perf_callchain_user_64() function into an infinite loop.
A malicious user could create a special stack layout that fools
the perf_callchain_user_64 function into an infinite loop, tying up
that particular CPU and the process can not be killed.
A kernel patch was committed upstream capping the maximum userlevel
stacktrace collected by perf to PERF_MAX_STACK_DEPTH on 64bit powerpc
architectures. This affects all ppc64 kernels that support perf.
This seems to be kind of local DOS that can be resolved when the system is
This issue does not affect the Linux kernels as shipped with Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG 2.
This issue affects the Linux kernels as shipped with Red Hat Enterprise Linux 7 and may be addressed in a future update.
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1253892]
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2015:2152 https://rhn.redhat.com/errata/RHSA-2015-2152.html