exec: do not sleep in TASK_TRACED under ->cred_guard_mutex
[pandora-kernel.git] / fs / exec.c
index fb4f3cd..172ceb6 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1015,6 +1015,35 @@ out:
 
 EXPORT_SYMBOL(flush_old_exec);
 
+/*
+ * Prepare credentials and lock ->cred_guard_mutex.
+ * install_exec_creds() commits the new creds and drops the lock.
+ * Or, if exec fails before, free_bprm() should release ->cred and
+ * and unlock.
+ */
+int prepare_bprm_creds(struct linux_binprm *bprm)
+{
+       if (mutex_lock_interruptible(&current->cred_guard_mutex))
+               return -ERESTARTNOINTR;
+
+       bprm->cred = prepare_exec_creds();
+       if (likely(bprm->cred))
+               return 0;
+
+       mutex_unlock(&current->cred_guard_mutex);
+       return -ENOMEM;
+}
+
+void free_bprm(struct linux_binprm *bprm)
+{
+       free_arg_pages(bprm);
+       if (bprm->cred) {
+               mutex_unlock(&current->cred_guard_mutex);
+               abort_creds(bprm->cred);
+       }
+       kfree(bprm);
+}
+
 /*
  * install the new credentials for this executable
  */
@@ -1024,12 +1053,13 @@ void install_exec_creds(struct linux_binprm *bprm)
 
        commit_creds(bprm->cred);
        bprm->cred = NULL;
-
-       /* cred_guard_mutex must be held at least to this point to prevent
+       /*
+        * cred_guard_mutex must be held at least to this point to prevent
         * ptrace_attach() from altering our determination of the task's
-        * credentials; any time after this it may be unlocked */
-
+        * credentials; any time after this it may be unlocked.
+        */
        security_bprm_committed_creds(bprm);
+       mutex_unlock(&current->cred_guard_mutex);
 }
 EXPORT_SYMBOL(install_exec_creds);
 
@@ -1246,14 +1276,6 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 
 EXPORT_SYMBOL(search_binary_handler);
 
-void free_bprm(struct linux_binprm *bprm)
-{
-       free_arg_pages(bprm);
-       if (bprm->cred)
-               abort_creds(bprm->cred);
-       kfree(bprm);
-}
-
 /*
  * sys_execve() executes a new program.
  */
@@ -1277,20 +1299,15 @@ int do_execve(char * filename,
        if (!bprm)
                goto out_files;
 
-       retval = -ERESTARTNOINTR;
-       if (mutex_lock_interruptible(&current->cred_guard_mutex))
+       retval = prepare_bprm_creds(bprm);
+       if (retval)
                goto out_free;
-       current->in_execve = 1;
-
-       retval = -ENOMEM;
-       bprm->cred = prepare_exec_creds();
-       if (!bprm->cred)
-               goto out_unlock;
 
        retval = check_unsafe_exec(bprm);
        if (retval < 0)
-               goto out_unlock;
+               goto out_free;
        clear_in_exec = retval;
+       current->in_execve = 1;
 
        file = open_exec(filename);
        retval = PTR_ERR(file);
@@ -1340,7 +1357,6 @@ int do_execve(char * filename,
        /* execve succeeded */
        current->fs->in_exec = 0;
        current->in_execve = 0;
-       mutex_unlock(&current->cred_guard_mutex);
        acct_update_integrals(current);
        free_bprm(bprm);
        if (displaced)
@@ -1360,10 +1376,7 @@ out_file:
 out_unmark:
        if (clear_in_exec)
                current->fs->in_exec = 0;
-
-out_unlock:
        current->in_execve = 0;
-       mutex_unlock(&current->cred_guard_mutex);
 
 out_free:
        free_bprm(bprm);