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Frederic Weisbecker bf26c01849 ptrace: Prepare to fix racy accesses on task breakpoints 
When a task is traced and is in a stopped state, the tracer
may execute a ptrace request to examine the tracee state and
get its task struct. Right after, the tracee can be killed
and thus its breakpoints released.
This can happen concurrently when the tracer is in the middle
of reading or modifying these breakpoints, leading to dereferencing
a freed pointer.

Hence, to prepare the fix, create a generic breakpoint reference
holding API. When a reference on the breakpoints of a task is
held, the breakpoints won't be released until the last reference
is dropped. After that, no more ptrace request on the task's
breakpoints can be serviced for the tracer.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: v2.6.33.. <stable@kernel.org>
Link: http://lkml.kernel.org/r/1302284067-7860-2-git-send-email-fweisbec@gmail.com
2011-04-25 17:28:24 +02:00
..
debug Fix common misspellings 2011-03-31 11:26:23 -03:00
gcov Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-03-20 18:14:55 -07:00
irq Merge branches 'x86-fixes-for-linus', 'sched-fixes-for-linus', 'timers-fixes-for-linus', 'irq-fixes-for-linus' and 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-04-07 12:12:58 -07:00
power fix XEN_SAVE_RESTORE Kconfig dependencies 2011-04-11 22:54:48 +02:00
time posix clocks: Replace mutex with reader/writer semaphore 2011-04-18 10:39:38 +02:00
trace block: make unplug timer trace event correspond to the schedule() unplug 2011-04-16 13:51:05 +02:00
.gitignore
acct.c
async.c
audit_tree.c Fix common misspellings 2011-03-31 11:26:23 -03:00
audit_watch.c kill path_lookup() 2011-03-14 09:15:23 -04:00
audit.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
audit.h
auditfilter.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
auditsc.c Fix common misspellings 2011-03-31 11:26:23 -03:00
backtracetest.c
bounds.c memcg: remove direct page_cgroup-to-page pointer 2011-03-23 19:46:28 -07:00
capability.c userns: make has_capability* into real functions 2011-03-23 19:47:06 -07:00
cgroup_freezer.c
cgroup.c Fix common misspellings 2011-03-31 11:26:23 -03:00
compat.c posix-timers: Introduce a syscall for clock tuning. 2011-02-02 15:28:19 +01:00
configs.c
cpu.c Fix common misspellings 2011-03-31 11:26:23 -03:00
cpuset.c cpuset: hold callback_mutex in cpuset_post_clone() 2011-03-23 19:46:35 -07:00
crash_dump.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
cred.c userns: security: make capabilities relative to the user namespace 2011-03-23 19:47:02 -07:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c ptrace: Prepare to fix racy accesses on task breakpoints 2011-04-25 17:28:24 +02:00
extable.c
fork.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
freezer.c Freezer: Fix a race during freezing of TASK_STOPPED tasks 2010-12-24 15:02:40 +01:00
futex_compat.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
futex.c futex: Set FLAGS_HAS_TIMEOUT during futex_wait restart setup 2011-04-15 16:34:32 +02:00
groups.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
hrtimer.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
hung_task.c
hw_breakpoint.c perf: Dynamic pmu types 2010-12-16 11:36:43 +01:00
irq_work.c irq_work: Use per cpu atomics instead of regular atomics 2010-12-18 15:54:48 +01:00
itimer.c
jump_label.c
kallsyms.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-25 17:52:22 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
kfifo.c
kmod.c
kprobes.c Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-01-07 17:02:58 -08:00
ksysfs.c
kthread.c Fix common misspellings 2011-03-31 11:26:23 -03:00
latencytop.c Fix common misspellings 2011-03-31 11:26:23 -03:00
lockdep_internals.h
lockdep_proc.c lockdep: Remove unused 'factor' variable from lockdep_stats_show() 2011-03-23 13:54:47 +01:00
lockdep_states.h
lockdep.c Fix common misspellings 2011-03-31 11:26:23 -03:00
Makefile crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
module.c Fix common misspellings 2011-03-31 11:26:23 -03:00
mutex-debug.c
mutex-debug.h
mutex.c Fix common misspellings 2011-03-31 11:26:23 -03:00
mutex.h
notifier.c
ns_cgroup.c
nsproxy.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
padata.c Fix common misspellings 2011-03-31 11:26:23 -03:00
panic.c move x86 specific oops=panic to generic code 2011-03-22 17:44:11 -07:00
params.c Fix common misspellings 2011-03-31 11:26:23 -03:00
perf_event.c perf_event: Fix cgrp event scheduling bug in perf_enable_on_exec() 2011-04-11 11:07:55 +02:00
pid_namespace.c pidns: call pid_ns_prepare_proc() from create_pid_namespace() 2011-03-23 19:46:58 -07:00
pid.c next_pidmap: fix overflow condition 2011-04-18 10:35:30 -07:00
pm_qos_params.c PM QoS: Make pm_qos settings readable 2011-03-15 00:43:18 +01:00
posix-cpu-timers.c Fix common misspellings 2011-03-31 11:26:23 -03:00
posix-timers.c Fix common misspellings 2011-03-31 11:26:23 -03:00
printk.c printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig 2011-03-22 17:44:13 -07:00
profile.c
ptrace.c ptrace: Prepare to fix racy accesses on task breakpoints 2011-04-25 17:28:24 +02:00
range.c
rcupdate.c rcu: add comment saying why DEBUG_OBJECTS_RCU_HEAD depends on PREEMPT. 2011-03-04 08:05:41 -08:00
rcutiny_plugin.h rcu: call __rcu_read_unlock() in exit_rcu for tiny RCU 2011-03-04 08:05:08 -08:00
rcutiny.c rcu: avoid pointless blocked-task warnings 2011-01-14 04:58:08 -08:00
rcutorture.c rcutorture: Get rid of duplicate sched.h include 2011-03-04 08:05:17 -08:00
rcutree_plugin.h rcu: increase synchronize_sched_expedited() batching 2010-12-17 12:34:08 -08:00
rcutree_trace.c rcu,cleanup: simplify the code when cpu is dying 2010-11-29 22:01:58 -08:00
rcutree.c Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-01-07 17:02:58 -08:00
rcutree.h rcu: limit rcu_node leaf-level fanout 2010-12-17 12:34:20 -08:00
relay.c
res_counter.c memcg: res_counter_read_u64(): fix potential races on 32-bit machines 2011-03-23 19:46:22 -07:00
resource.c resources: add arch hook for preventing allocation in reserved areas 2010-12-17 10:01:09 -08:00
rtmutex_common.h rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.h
rtmutex-tester.c rtmutex: tester: Remove the remaining BKL leftovers 2011-02-22 22:07:22 +01:00
rtmutex.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex.h
rwsem.c
sched_autogroup.c Fix common misspellings 2011-03-31 11:26:23 -03:00
sched_autogroup.h sched, autogroup: Stop going ahead if autogroup is disabled 2011-02-23 11:33:59 +01:00
sched_clock.c sched: Add some clock info to sched_debug 2010-11-23 10:29:08 +01:00
sched_cpupri.c
sched_cpupri.h
sched_debug.c sched: Use a buddy to implement yield_task_fair() 2011-02-03 14:20:33 +01:00
sched_fair.c sched: Fix erroneous all_pinned logic 2011-04-11 11:08:54 +02:00
sched_features.h
sched_idletask.c sched, doc: Update sched-design-CFS.txt 2011-03-23 14:09:41 +01:00
sched_rt.c Fix common misspellings 2011-03-31 11:26:23 -03:00
sched_stats.h
sched_stoptask.c sched, doc: Update sched-design-CFS.txt 2011-03-23 14:09:41 +01:00
sched.c block: let io_schedule() flush the plug inline 2011-04-16 13:27:55 +02:00
seccomp.c
semaphore.c
signal.c signal.c: fix erroneous syscall kernel-doc 2011-04-08 11:05:24 -07:00
smp.c smp: move smp setup functions to kernel/smp.c 2011-03-22 17:44:11 -07:00
softirq.c Fix common misspellings 2011-03-31 11:26:23 -03:00
spinlock.c
srcu.c rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status 2011-01-14 04:56:49 -08:00
stacktrace.c
stop_machine.c kthread: use kthread_create_on_node() 2011-03-22 17:44:01 -07:00
sys_ni.c vfs: Add open by file handle support 2011-03-15 02:21:44 -04:00
sys.c userns: user namespaces: convert all capable checks in kernel/sys.c 2011-03-23 19:47:06 -07:00
sysctl_binary.c open-style analog of vfs_path_lookup() 2011-03-14 09:15:28 -04:00
sysctl_check.c sysctl_check: drop dead code 2011-03-23 19:46:51 -07:00
sysctl.c sysctl: restrict write access to dmesg_restrict 2011-03-23 19:46:54 -07:00
taskstats.c taskstats: use appropriate printk priority level 2011-03-23 19:47:14 -07:00
test_kprobes.c
time.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
timeconst.pl
timer.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
tracepoint.c tracepoints: Fix section alignment using pointer array 2011-02-03 09:28:46 -05:00
tsacct.c
uid16.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
up.c
user_namespace.c user_ns: improve the user_ns on-the-slab packaging 2011-01-13 08:03:18 -08:00
user-return-notifier.c Fix common misspellings 2011-03-31 11:26:23 -03:00
user.c userns: add a user_namespace as creator/owner of uts_namespace 2011-03-23 19:46:59 -07:00
utsname_sysctl.c
utsname.c userns: allow sethostname in a container 2011-03-23 19:47:03 -07:00
wait.c Fix common misspellings 2011-03-31 11:26:23 -03:00
watchdog.c kernel/watchdog.c: always return NOTIFY_OK during cpu up/down events 2011-03-22 17:44:12 -07:00
workqueue_sched.h
workqueue.c Fix common misspellings 2011-03-31 11:26:23 -03:00