hw breakpoints: Fix pid namespace bug

commit 068e35eee9ef98eb4cab55181977e24995d273be upstream.

Hardware breakpoints can't be registered within pid namespaces
because tsk->pid is passed rather than the pid in the current
namespace.

(See https://bugzilla.kernel.org/show_bug.cgi?id=17281 )

This is a quick fix demonstrating the problem but is not the
best method of solving the problem since passing pids internally
is not the best way to avoid pid namespace bugs. Subsequent patches
will show a better solution.

Much thanks to Frederic Weisbecker <fweisbec@gmail.com> for doing
the bulk of the work finding this bug.

Reported-by: Robin Green <greenrd@greenrd.org>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
LKML-Reference: <f63454af09fb1915717251570423eb9ddd338340.1284407762.git.matthltc@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 7a56b22e0602f0b37338c189110d65c07e7cc730..6eb6422197135383a4231db0780e319ddd501153 100644 (file)
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -417,7 +417,8 @@ register_user_hw_breakpoint(struct perf_event_attr *attr,
                            perf_overflow_handler_t triggered,
                            struct task_struct *tsk)
 {
-       return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
+       return perf_event_create_kernel_counter(attr, -1, task_pid_vnr(tsk),
+                                               triggered);
 }
 EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);