From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Fri, 1 Jun 2007 07:46:53 +0000 (-0700)
Subject: tty: fix leakage of -ERESTARTSYS to userland
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=040b6362d58fe9a344e053546c12bf821f6fce99;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

tty: fix leakage of -ERESTARTSYS to userland

Spotted by Satoru Takeuchi.

kill_pgrp(task_pgrp(current)) sends the signal to the current's thread
group, but can choose any sub-thread as a target for signal_wake_up().
This means that job_control() and tty_check_change() may return
-ERESTARTSYS without signal_pending().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index b3d4ccc33a47..154f42203b05 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -1191,6 +1191,7 @@ static int job_control(struct tty_struct *tty, struct file *file)
 			    is_current_pgrp_orphaned())
 				return -EIO;
 			kill_pgrp(task_pgrp(current), SIGTTIN, 1);
+			set_thread_flag(TIF_SIGPENDING);
 			return -ERESTARTSYS;
 		}
 	}
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 75d2a46e106f..3752edc30c36 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1148,7 +1148,8 @@ int tty_check_change(struct tty_struct * tty)
 		return 0;
 	if (is_current_pgrp_orphaned())
 		return -EIO;
-	(void) kill_pgrp(task_pgrp(current), SIGTTOU, 1);
+	kill_pgrp(task_pgrp(current), SIGTTOU, 1);
+	set_thread_flag(TIF_SIGPENDING);
 	return -ERESTARTSYS;
 }