2 files changed, 23 insertions, 23 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index f38da6bda269..773469703c62 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -536,29 +536,15 @@ static int proc_fd_access_allowed(struct inode *inode)
 {
         struct task_struct *task;
         int allowed = 0;
-        /* Allow access to a task's file descriptors if either we may
-         * use ptrace attach to the process and find out that
-         * information, or if the task cannot possibly be ptraced
-         * allow access if we have the proper capability.
+        /* Allow access to a task's file descriptors if it is us or we
+         * may use ptrace attach to the process and find out that
+         * information.
          */
         task = get_proc_task(inode);
-        if (task == current)
-                allowed = 1;
-        if (task && !allowed) {
-                int alive;
-
-                task_lock(task);
-                alive = !!task->mm;
-                task_unlock(task);
-                if (alive)
-                        /* For a living task obey ptrace_may_attach */
-                        allowed = ptrace_may_attach(task);
-                else
-                        /* For a special task simply check the capability */
-                        allowed = capable(CAP_SYS_PTRACE);
-        }
-        if (task)
+        if (task) {
+                allowed = ptrace_may_attach(task);
                 put_task_struct(task);
+        }
         return allowed;
 }
 
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 921c22ad16e4..6252d2fa2bf3 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;