[PATCH 5.15 055/123] HID: hid-lg4ff: Add check for empty lbuf

Greg Kroah-Hartman
2022-12-12T13:29:03Z

From: Anastasia Belova <abelova@astralinux.ru>

commit d180b6496143cd360c5d5f58ae4b9a8229c1f344 upstream.

If an empty buf is received, lbuf is also empty. So lbuf is
accessed by index -1.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: f31a2de3fe36 ("HID: hid-lg4ff: Allow switching of Logitech gaming wheels between compatibility modes")
Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hid/hid-lg4ff.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/hid/hid-lg4ff.c
+++ b/drivers/hid/hid-lg4ff.c
@@ -872,6 +872,12 @@ static ssize_t lg4ff_alternate_modes_sto
return -ENOMEM;

i = strlen(lbuf);
+
+ if (i == 0) {
+ kfree(lbuf);
+ return -EINVAL;
+ }
+
if (lbuf[i-1] == '\n') {
if (i == 1) {
kfree(lbuf);