thermal/core: Potential buffer overflow in thermal_build_list_of_policies()

After printing the list of thermal governors, then this function prints
a newline character.  The problem is that "size" has not been updated
after printing the last governor.  This means that it can write one
character (the NUL terminator) beyond the end of the buffer.

Get rid of the "size" variable and just use "PAGE_SIZE - count" directly.

Fixes: 1b4f48494e ("thermal: core: group functions related to governor handling")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210916131342.GB25094@kili
This commit is contained in:
Dan Carpenter 2021-09-16 16:13:42 +03:00 committed by Daniel Lezcano
parent 8b4bd25667
commit 1bb30b20b4

View file

@ -222,15 +222,14 @@ int thermal_build_list_of_policies(char *buf)
{
struct thermal_governor *pos;
ssize_t count = 0;
ssize_t size = PAGE_SIZE;
mutex_lock(&thermal_governor_lock);
list_for_each_entry(pos, &thermal_governor_list, governor_list) {
size = PAGE_SIZE - count;
count += scnprintf(buf + count, size, "%s ", pos->name);
count += scnprintf(buf + count, PAGE_SIZE - count, "%s ",
pos->name);
}
count += scnprintf(buf + count, size, "\n");
count += scnprintf(buf + count, PAGE_SIZE - count, "\n");
mutex_unlock(&thermal_governor_lock);