This is a note to let you know that I've just added the patch titled thermal/core: Potential buffer overflow in thermal_build_list_of_policies() to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: thermal-core-potential-buffer-overflow-in-thermal_bu.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 743b225785c5fd7d49f618ec140171ca52a2d41b Author: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Date: Thu Sep 16 16:13:42 2021 +0300 thermal/core: Potential buffer overflow in thermal_build_list_of_policies() [ Upstream commit 1bb30b20b49773369c299d4d6c65227201328663 ] 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: 1b4f48494eb2 ("thermal: core: group functions related to governor handling") Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210916131342.GB25094@kili Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c index 97ef9b040b84..51374f4e1cca 100644 --- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -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);