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diff --git a/share/security/advisories/FreeBSD-EN-10:02.sched_ule.asc b/share/security/advisories/FreeBSD-EN-10:02.sched_ule.asc deleted file mode 100644 index 384ae179fc..0000000000 --- a/share/security/advisories/FreeBSD-EN-10:02.sched_ule.asc +++ /dev/null @@ -1,157 +0,0 @@ ------BEGIN PGP SIGNED MESSAGE----- -Hash: SHA1 - -============================================================================= -FreeBSD-EN-10:02.sched_ule Errata Notice - The FreeBSD Project - -Topic: Deadlock in ULE scheduler - -Category: core -Module: kern -Announced: 2010-02-27 -Credits: Attilio Rao -Affects: FreeBSD 7.0, 7.1, and 7.2. -Corrected: 2009-09-24 09:08:22 UTC (RELENG_7, 7.2-STABLE) - 2010-02-27 10:55:43 UTC (RELENG_7_2, 7.2-RELEASE-p7) - 2010-02-27 10:55:43 UTC (RELENG_7_1, 7.1-RELEASE-p11) - -For general information regarding FreeBSD Errata Notices and Security -Advisories, including descriptions of the fields above, security -branches, and the following sections, please visit -<URL:http://security.freebsd.org/>. - -I. Background - -FreeBSD has two schedulers: the classic 4BSD scheduler and a newer, -more SMP-aware scheduler called ULE. The 4BSD scheduler was the -default scheduler until FreeBSD 7.0. Starting with FreeBSD 7.1 the -default scheduler is ULE. - -The scheduler is responsible for allocating CPU time to threads and -assigning threads to CPUs. Runnable threads (i.e. threads which are -not waiting for a blocking operation, such as an I/O operation, memory -allocation or lock acquisition, to complete) are assigned to a CPU and -placed in that CPU's run queue. Each thread and each CPU's run queue -is protected by a separate lock. - -II. Problem Description - -When a thread is reassigned from one CPU to another, the scheduler -first acquires the thread's lock, then releases the source CPU's run -queue lock. The scheduler then acquires the target CPU's run queue -lock and holds the lock while it adds the thread to the queue and signals -the target CPU. Finally it reacquires the source CPU's run queue lock -before unlocking the thread. A thread on the target CPU, having been -notified of the reassigned thread's arrival on the target CPU's run -queue, will then acquire the thread's lock before switching it in. - -If, at the same time, a third thread tries to acquire both the source -and target CPUs' run queue locks, a three-way deadlock may occur: - - - The second thread has acquired the target CPU's run queue lock, but - has not yet acquired the first thread's lock. - - - The third thread has acquired the source CPU's run queue lock, and - is waiting to acquire the target CPU's run queue lock, which is - locked by the second thread. - - - The first thread is waiting to acquire the source CPU's run queue - lock, which is held by the third thread, in order to release its - own lock. - -As a result both CPUs' run queues are locked, and each of the three -threads is waiting to acquire a lock held by one of the others. - -Eventually every CPU in the system ends up in a state where it is -waiting to acquire each other's locks. - -It has not been determined whether this also affects single-CPU -systems but it is recommended this Errata Notice be applied to -single-CPU systems as well. - -III. Impact - -Affected systems may become deadlocked and require power-cycling. The -chance of a deadlock occurring increases with the number of CPUs. -There may be other aggravating factors such as running powerd(8). But -eventually any multi-processor system using the ULE scheduler will -become deadlocked. - -IV. Workaround - -Replace SCHED_ULE with SCHED_4BSD in your kernel configuration, -recompile your kernel and reboot the system. - -Note that systems running the 4BSD scheduler are not affected; to -determine what scheduler a system is using, run -# sysctl kern.sched.name - -V. Solution - -Perform one of the following: - -1) Upgrade your system to 7-STABLE, or to the RELENG_7_2 or RELENG_7_1 -security branch dated after the correction date. - -2) To patch your present system: - -The following patches have been verified to apply to FreeBSD 7.1 and -7.2 systems. - -a) Download the relevant patch from the location below, and verify the - detached PGP signature using your PGP utility. - -# fetch http://security.FreeBSD.org/patches/EN-10:02/sched_ule.patch -# fetch http://security.FreeBSD.org/patches/EN-10:02/sched_ule.patch.asc - -b) Apply the patch. - -# cd /usr/src -# patch < /path/to/patch - -c) Recompile your kernel as described in -<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the -system. - -VI. Correction details - -The following list contains the revision numbers of each file that was -corrected in FreeBSD. - -CVS: - -Branch Revision - Path -- ------------------------------------------------------------------------- -RELENG_7 - src/sys/kern/sched_ule.c 1.214.2.9 -RELENG_7_2 - src/UPDATING 1.507.2.23.2.10 - src/sys/conf/newvers.sh 1.72.2.11.2.11 - src/sys/kern/sched_ule.c 1.214.2.8.2.2 -RELENG_7_1 - src/UPDATING 1.507.2.13.2.14 - src/sys/conf/newvers.sh 1.72.2.9.2.15 - src/sys/kern/sched_ule.c 1.214.2.7.2.2 - -Subversion: - -Branch/path Revision -- ------------------------------------------------------------------------- -stable/7/ r197453 -releng/7.2/ r204409 -releng/7.1/ r204409 -- ------------------------------------------------------------------------- - -VII. References - -The latest revision of this advisory is available at -http://security.FreeBSD.org/advisories/FreeBSD-EN-10:02.sched_ule.asc ------BEGIN PGP SIGNATURE----- -Version: GnuPG v1.4.10 (FreeBSD) - -iEYEARECAAYFAkuI+1oACgkQFdaIBMps37ItgACghSdnagnmy9Zohrh5IKuhygiy -kVsAn2EXtts/l+IrjuWIzODSSUzLylia -=mj/v ------END PGP SIGNATURE----- |