From 1c1062c5cf215c960373c75acb96dc601714ed88 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 16 Sep 2021 16:13:42 +0300 Subject: [PATCH] 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 Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20210916131342.GB25094@kili Signed-off-by: Sasha Levin --- drivers/thermal/thermal_core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c index f526ce31f5a2..20eab56b02cb 100644 --- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -228,15 +228,14 @@ 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);