1 files changed, 38 insertions, 25 deletions

diff --git a/fs/exec.c b/fs/exec.c
index fb4f3cd..172ceb6 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1016,6 +1016,35 @@ 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
  */
 void install_exec_creds(struct linux_binprm *bprm)
@@ -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);