um: fix races between line_open() and line_config()
Pull parse_chan_pair() call into setup_one_line(), under the mutex.
We really don't want open() to succeed before parse_chan_pair() had
been done (or after it has failed, BTW). We also want "remove con<n>"
to free irqs, etc., same as "config con<n>=none".
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index dc7e216..1a8d659 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -482,7 +482,7 @@
}
static int setup_one_line(struct line *lines, int n, char *init,
- char **error_out)
+ const struct chan_opts *opts, char **error_out)
{
struct line *line = &lines[n];
int err = -EINVAL;
@@ -494,13 +494,28 @@
goto out;
}
- if (!strcmp(init, "none"))
- line->valid = 0;
- else {
- line->init_str = init;
+ if (!strcmp(init, "none")) {
+ if (line->valid) {
+ line->valid = 0;
+ kfree(line->init_str);
+ parse_chan_pair(NULL, line, n, opts, error_out);
+ err = 0;
+ }
+ } else {
+ char *new = kstrdup(init, GFP_KERNEL);
+ if (!new) {
+ *error_out = "Failed to allocate memory";
+ return -ENOMEM;
+ }
+ line->init_str = new;
line->valid = 1;
+ err = parse_chan_pair(new, line, n, opts, error_out);
+ if (err) {
+ line->init_str = NULL;
+ line->valid = 0;
+ kfree(new);
+ }
}
- err = 0;
out:
mutex_unlock(&line->count_lock);
return err;
@@ -549,10 +564,8 @@
int line_config(struct line *lines, unsigned int num, char *str,
const struct chan_opts *opts, char **error_out)
{
- struct line *line;
- char *new;
char *end;
- int n, err;
+ int n;
if (*str == '=') {
*error_out = "Can't configure all devices from mconsole";
@@ -569,16 +582,7 @@
return -EINVAL;
}
- new = kstrdup(end, GFP_KERNEL);
- if (new == NULL) {
- *error_out = "Failed to allocate memory";
- return -ENOMEM;
- }
- err = setup_one_line(lines, n, new, error_out);
- if (err)
- return err;
- line = &lines[n];
- return parse_chan_pair(line->init_str, line, n, opts, error_out);
+ return setup_one_line(lines, n, end, opts, error_out);
}
int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
@@ -633,7 +637,7 @@
*error_out = "Device number out of range";
return -EINVAL;
}
- return setup_one_line(lines, n, "none", error_out);
+ return setup_one_line(lines, n, "none", NULL, error_out);
}
struct tty_driver *register_lines(struct line_driver *line_driver,
@@ -688,15 +692,9 @@
if (line->init_str == NULL)
continue;
- line->init_str = kstrdup(line->init_str, GFP_KERNEL);
- if (line->init_str == NULL)
- printk(KERN_ERR "lines_init - kstrdup returned NULL\n");
-
- if (parse_chan_pair(line->init_str, line, i, opts, &error)) {
- printk(KERN_ERR "parse_chan_pair failed for "
+ if (setup_one_line(lines, i, line->init_str, opts, &error))
+ printk(KERN_ERR "setup_one_line failed for "
"device %d : %s\n", i, error);
- line->valid = 0;
- }
}
}