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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>
This commit is contained in:
Alan Cox 2009-06-11 12:46:41 +01:00 committed by Linus Torvalds
parent 620df3c0a5
commit 5f0878acba
1 changed files with 7 additions and 6 deletions
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13
drivers/char/tty_io.c
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@ -295,7 +295,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
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 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
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;