tty: Fix oops when scanning the polling list for kgdb
Costantino Leandro found a bug in tty_find_polling_driver and provided a
patch that fixed the crash but not the underlying bug. This fixes the
underlying bug where the list walk corrupts the values it is using on a
match but then reuses them if the open fails.
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 66b99a2..6c81739 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -295,7 +295,7 @@
struct tty_driver *p, *res = NULL;
int tty_line = 0;
int len;
- char *str;
+ char *str, *stp;
for (str = name; *str; str++)
if ((*str >= '0' && *str <= '9') || *str == ',')
@@ -311,13 +311,14 @@
list_for_each_entry(p, &tty_drivers, tty_drivers) {
if (strncmp(name, p->name, len) != 0)
continue;
- if (*str == ',')
- str++;
- if (*str == '\0')
- str = NULL;
+ stp = str;
+ if (*stp == ',')
+ stp++;
+ if (*stp == '\0')
+ stp = NULL;
if (tty_line >= 0 && tty_line <= p->num && p->ops &&
- p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
+ p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
res = tty_driver_kref_get(p);
*line = tty_line;
break;