Merge rsync://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

Conflicts:

	include/linux/kernel.h

1 files changed, 19 insertions, 4 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 921c22ad16e4..335c5b932e14 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -120,8 +120,18 @@ int ptrace_check_attach(struct task_struct *child, int kill)
 
 static int may_attach(struct task_struct *task)
 {
-	if (!task->mm)
-		return -EPERM;
+	/* May we inspect the given task?
+	 * This check is used both for attaching with ptrace
+	 * and for allowing access to sensitive information in /proc.
+	 *
+	 * ptrace_attach denies several cases that /proc allows
+	 * because setting up the necessary parent/child relationship
+	 * or halting the specified task is impossible.
+	 */
+	int dumpable = 0;
+	/* Don't let security modules deny introspection */
+	if (task == current)
+		return 0;
 	if (((current->uid != task->euid) ||
 	     (current->uid != task->suid) ||
 	     (current->uid != task->uid) ||
@@ -130,7 +140,9 @@ static int may_attach(struct task_struct *task)
 	     (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
 		return -EPERM;
 	smp_rmb();
-	if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+	if (task->mm)
+		dumpable = task->mm->dumpable;
+	if (!dumpable && !capable(CAP_SYS_PTRACE))
 		return -EPERM;
 
 	return security_ptrace(current, task);
@@ -176,6 +188,8 @@ repeat:
 		goto repeat;
 	}
 
+	if (!task->mm)
+		goto bad;
 	/* the same process cannot be attached many times */
 	if (task->ptrace & PT_PTRACED)
 		goto bad;
@@ -200,7 +214,7 @@ out:
 	return retval;
 }
 
-void __ptrace_detach(struct task_struct *child, unsigned int data)
+static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
 {
 	child->exit_code = data;
 	/* .. re-parent .. */
@@ -219,6 +233,7 @@ int ptrace_detach(struct task_struct *child, unsigned int data)
 	ptrace_disable(child);
 
 	write_lock_irq(&tasklist_lock);
+	/* protect against de_thread()->release_task() */
 	if (child->ptrace)
 		__ptrace_detach(child, data);
 	write_unlock_irq(&tasklist_lock);