1 files changed, 9 insertions, 0 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index b9d5f4e4f6a4..f764b8806955 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -171,6 +171,14 @@ int ptrace_attach(struct task_struct *task)
         if (same_thread_group(task, current))
                 goto out;
 
+        /* Protect exec's credential calculations against our interference;
+         * SUID, SGID and LSM creds get determined differently under ptrace.
+         */
+        retval = mutex_lock_interruptible(&current->cred_exec_mutex);
+        if (retval  < 0)
+                goto out;
+
+        retval = -EPERM;
 repeat:
         /*
          * Nasty, nasty.
@@ -210,6 +218,7 @@ repeat:
 bad:
         write_unlock_irqrestore(&tasklist_lock, flags);
         task_unlock(task);
+        mutex_unlock(&current->cred_exec_mutex);
 out:
         return retval;
 }