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>
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@ -295,7 +295,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
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struct tty_driver *p, *res = NULL;
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int tty_line = 0;
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int len;
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char *str;
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char *str, *stp;
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for (str = name; *str; str++)
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if ((*str >= '0' && *str <= '9') || *str == ',')
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@ -311,13 +311,14 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
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list_for_each_entry(p, &tty_drivers, tty_drivers) {
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if (strncmp(name, p->name, len) != 0)
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continue;
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if (*str == ',')
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str++;
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if (*str == '\0')
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str = NULL;
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stp = str;
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if (*stp == ',')
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stp++;
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if (*stp == '\0')
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stp = NULL;
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if (tty_line >= 0 && tty_line <= p->num && p->ops &&
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p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
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p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
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res = tty_driver_kref_get(p);
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*line = tty_line;
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break;
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