[PATCH 6.18 503/752] HID: prodikeys: Check presence of pm->input_ep82

Sasha Levin
2026-02-28T17:55:17Z

From: Günther Noack <gnoack@google.com>

[ Upstream commit cee8337e1bad168136aecfe6416ecd7d3aa7529a ]

Fake USB devices can send their own report descriptors for which the
input_mapping() hook does not get called. In this case, pm->input_ep82 stays
NULL, which leads to a crash later.

This does not happen with the real device, but can be provoked by imposing as
one.

Cc: stable@vger.kernel.org
Signed-off-by: Günther Noack <gnoack@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hid/hid-prodikeys.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/hid/hid-prodikeys.c b/drivers/hid/hid-prodikeys.c
index 74bddb2c3e82e..6e413df38358a 100644
--- a/drivers/hid/hid-prodikeys.c
+++ b/drivers/hid/hid-prodikeys.c
@@ -378,6 +378,10 @@ static int pcmidi_handle_report4(struct pcmidi_snd *pm, u8 *data)
bit_mask = (bit_mask << 8) | data[2];
bit_mask = (bit_mask << 8) | data[3];

+ /* robustness in case input_mapping hook does not get called */
+ if (!pm->input_ep82)
+ return 0;
+
/* break keys */
for (bit_index = 0; bit_index < 24; bit_index++) {
if (!((0x01 << bit_index) & bit_mask)) {
--
2.51.0