From 4a30c12542290f1def08b9ef0d677c024c500589 Mon Sep 17 00:00:00 2001 From: Daniel Rosenberg Date: Mon, 2 Jul 2018 16:59:37 -0700 Subject: [PATCH] HID: debug: check length before copy_to_user() commit 717adfdaf14704fd3ec7fa2c04520c0723247eac upstream. If our length is greater than the size of the buffer, we overflow the buffer Cc: stable@vger.kernel.org Signed-off-by: Daniel Rosenberg Reviewed-by: Benjamin Tissoires CVE: CVE-2018-9516 Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=4a30c12542290f1def08b9ef0d677c024c500589] Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andreas Wellving --- drivers/hid/hid-debug.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c index acfb522a432a..29423691c105 100644 --- a/drivers/hid/hid-debug.c +++ b/drivers/hid/hid-debug.c @@ -1152,6 +1152,8 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer, goto out; if (list->tail > list->head) { len = list->tail - list->head; + if (len > count) + len = count; if (copy_to_user(buffer + ret, &list->hid_debug_buf[list->head], len)) { ret = -EFAULT; @@ -1161,6 +1163,8 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer, list->head += len; } else { len = HID_DEBUG_BUFSIZE - list->head; + if (len > count) + len = count; if (copy_to_user(buffer, &list->hid_debug_buf[list->head], len)) { ret = -EFAULT; @@ -1168,7 +1172,9 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer, } list->head = 0; ret += len; - goto copy_rest; + count -= len; + if (count > 0) + goto copy_rest; } }