--- zzzz-none-000/linux-3.10.107/arch/um/drivers/line.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/um/drivers/line.c	2021-02-04 17:41:59.000000000 +0000
@@ -632,6 +632,7 @@
 	int fd = winch->fd;
 	int err;
 	char c;
+	struct pid *pgrp;
 
 	if (fd != -1) {
 		err = generic_read(fd, &c, NULL);
@@ -657,7 +658,10 @@
 		if (line != NULL) {
 			chan_window_size(line, &tty->winsize.ws_row,
 					 &tty->winsize.ws_col);
-			kill_pgrp(tty->pgrp, SIGWINCH, 1);
+			pgrp = tty_get_pgrp(tty);
+			if (pgrp)
+				kill_pgrp(pgrp, SIGWINCH, 1);
+			put_pid(pgrp);
 		}
 		tty_kref_put(tty);
 	}