From 5534ecb2dda04345e8243901e0e49599228b4273 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Sat, 27 Feb 2010 19:49:37 +0100
Subject: ptrace: kill BKL in ptrace syscall

The comment suggests that this usage is stale. There is no bkl in the
exec path so if there is a race lurking there, the bkl in ptrace is
not going to help in this regard.

Overview of the possibility of "accidental" races this bkl might
protect:

- ptrace_traceme() is protected against task removal and concurrent
read/write on current->ptrace as it locks write tasklist_lock.

- arch_ptrace_attach() is serialized by ptrace_traceme() against
concurrent PTRACE_TRACEME or PTRACE_ATTACH

- ptrace_attach() is protected the same way ptrace_traceme() and
in turn serializes arch_ptrace_attach()

- ptrace_check_attach() does its own well described serializing too.

There is no obvious race here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Roland McGrath <roland@redhat.com>
---
 kernel/ptrace.c | 10 ----------
 1 file changed, 10 deletions(-)

(limited to 'kernel')

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 42ad8ae729a0..53575020f82b 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -666,10 +666,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
 	struct task_struct *child;
 	long ret;
 
-	/*
-	 * This lock_kernel fixes a subtle race with suid exec
-	 */
-	lock_kernel();
 	if (request == PTRACE_TRACEME) {
 		ret = ptrace_traceme();
 		if (!ret)
@@ -703,7 +699,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
  out_put_task_struct:
 	put_task_struct(child);
  out:
-	unlock_kernel();
 	return ret;
 }
 
@@ -813,10 +808,6 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 	struct task_struct *child;
 	long ret;
 
-	/*
-	 * This lock_kernel fixes a subtle race with suid exec
-	 */
-	lock_kernel();
 	if (request == PTRACE_TRACEME) {
 		ret = ptrace_traceme();
 		goto out;
@@ -846,7 +837,6 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
  out_put_task_struct:
 	put_task_struct(child);
  out:
-	unlock_kernel();
 	return ret;
 }
 #endif	/* CONFIG_COMPAT */
-- 
cgit v1.2.3-58-ga151


From b8bc1389b74c2b66255651a6fcfae56c78b6e63f Mon Sep 17 00:00:00 2001
From: Alessio Igor Bogani <abogani@texware.it>
Date: Sun, 25 Apr 2010 13:18:48 +0200
Subject: ptrace: Cleanup useless header

BKL isn't present anymore into this file thus we can safely remove
smp_lock.h inclusion.

Signed-off-by: Alessio Igor Bogani <abogani@texware.it>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: James Morris <jmorris@namei.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/ptrace.c | 1 -
 1 file changed, 1 deletion(-)

(limited to 'kernel')

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 53575020f82b..2f0f50b450a3 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -14,7 +14,6 @@
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
-#include <linux/smp_lock.h>
 #include <linux/ptrace.h>
 #include <linux/security.h>
 #include <linux/signal.h>
-- 
cgit v1.2.3-58-ga151