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dadac81b1b
linux/kernel
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Oleg Nesterov dadac81b1b [PATCH] fix kill_proc_info() vs fork() theoretical race 
copy_process:

	attach_pid(p, PIDTYPE_PID, p->pid);
	attach_pid(p, PIDTYPE_TGID, p->tgid);

What if kill_proc_info(p->pid) happens in between?

copy_process() holds current->sighand.siglock, so we are safe
in CLONE_THREAD case, because current->sighand == p->sighand.

Otherwise, p->sighand is unlocked, the new process is already
visible to the find_task_by_pid(), but have a copy of parent's
'struct pid' in ->pids[PIDTYPE_TGID].

This means that __group_complete_signal() may hang while doing

	do ... while (next_thread() != p)

We can solve this problem if we reverse these 2 attach_pid()s:

	attach_pid() does wmb()

	group_send_sig_info() calls spin_lock(), which
	provides a read barrier. // Yes ?

I don't think we can hit this race in practice, but still.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-15 10:21:24 -08:00
..
irq [PATCH] kernel/: small cleanups 2006-01-08 20:13:48 -08:00
power [PATCH] Fix build failure in recent pm_prepare_* changes. 2006-02-07 16:12:33 -08:00
.gitignore
acct.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
audit.c [PATCH] EDAC: atomic scrub operations 2006-01-18 19:20:30 -08:00
auditsc.c [PATCH] EDAC: atomic scrub operations 2006-01-18 19:20:30 -08:00
capability.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
compat.c [PATCH] remove bogus asm/bug.h includes. 2006-02-07 20:56:35 -05:00
configs.c
cpu.c
cpuset.c [PATCH] cpuset: fix sparse warning 2006-02-03 08:32:06 -08:00
dma.c
exec_domain.c
exit.c [PATCH] Unlinline a bunch of other functions 2006-01-14 18:27:06 -08:00
extable.c
fork.c [PATCH] fix kill_proc_info() vs fork() theoretical race 2006-02-15 10:21:24 -08:00
futex.c
hrtimer.c [PATCH] hrtimer: round up relative start time on low-res arches 2006-02-14 16:09:35 -08:00
intermodule.c [PATCH] missing license tag in intermodule 2006-02-05 11:06:52 -08:00
itimer.c [PATCH] hrtimers: fix oldvalue return in setitimer 2006-02-01 08:53:12 -08:00
kallsyms.c
Kconfig.hz
Kconfig.preempt
kexec.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
kfifo.c
kmod.c
kprobes.c [PATCH] Kprobes: Fix deadlock in function-return probes 2006-02-03 08:32:00 -08:00
ksysfs.c [PATCH] kdump: export per cpu crash notes pointer through sysfs 2006-01-10 08:01:26 -08:00
kthread.c
Makefile [PATCH] build kernel/intermodule.c only when required 2006-01-16 23:15:26 -08:00
module.c [PATCH] module: strlen_user() race fix 2006-02-07 16:12:32 -08:00
mutex-debug.c [PATCH] fix/simplify mutex debugging code 2006-01-11 08:14:16 -08:00
mutex-debug.h [PATCH] mutex subsystem, debugging code 2006-01-09 15:59:20 -08:00
mutex.c [PATCH] mutex: trivial whitespace cleanups 2006-01-10 14:27:59 -08:00
mutex.h [PATCH] mutex subsystem, core 2006-01-09 15:59:19 -08:00
panic.c [PATCH] prevent recursive panic from softlockup watchdog 2006-02-10 08:13:12 -08:00
params.c
pid.c [PATCH] RCU signal handling 2006-01-08 20:13:40 -08:00
posix-cpu-timers.c [PATCH] hrtimer: switch clock_nanosleep to hrtimer nanosleep API 2006-01-10 08:01:38 -08:00
posix-timers.c [PATCH] kernel/posix-timers.c: remove do_posix_clock_notimer_create() 2006-02-01 08:53:13 -08:00
printk.c correct email address of Manfred Spraul 2006-01-15 02:43:54 +01:00
profile.c
ptrace.c [PATCH] compound page: no access_process_vm check 2006-02-14 16:09:33 -08:00
rcupdate.c [PATCH] rcu: fix hotplug-cpu ->donelist leak 2006-01-10 08:49:47 -08:00
rcutorture.c [PATCH] rcu_torture_lock deadlock fix 2006-01-31 11:30:18 -08:00
resource.c [PATCH] kernel/resource.c: __check_region(): remove pointless __deprecated 2006-01-10 08:02:02 -08:00
sched.c [PATCH] sched: revert "filter affine wakeups" 2006-02-14 16:09:34 -08:00
seccomp.c
signal.c [PATCH] do_sigaction: cleanup ->sa_mask manipulation 2006-02-09 16:17:36 -08:00
softirq.c
softlockup.c
spinlock.c
stop_machine.c [PATCH] Remove set_fs() in stop_machine() 2006-01-10 08:01:25 -08:00
sys_ni.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc-merge 2006-01-09 10:03:44 -08:00
sys.c [PATCH] kernel/sys.c NULL noise removal 2006-02-07 20:57:47 -05:00
sysctl.c [PATCH] zone_reclaim: configurable off node allocation period. 2006-02-01 08:53:16 -08:00
time.c [PATCH] Normalize timespec for negative values in ns_to_timespec 2006-02-03 08:32:06 -08:00
timer.c [PATCH] timer.c NULL noise removal 2006-02-07 20:57:42 -05:00
uid16.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
user.c [PATCH] "Fix uidhash_lock <-> RXU deadlock" fix 2006-01-31 16:49:43 -08:00
wait.c
workqueue.c [PATCH] Unlinline a bunch of other functions 2006-01-14 18:27:06 -08:00