lg4ff_raw_event() rewrites fixed report offsets when combined pedals are
enabled. It currently assumes that each product report contains every
source and destination byte used by the rewrite.

Return without rewriting a short report before each product-specific
access. Apply the same bound to the computed offset path.

Fixes: c832f86effbc ("HID: hid-logitech: Add combined pedal support Logitech wheels")
Signed-off-by: Jiancheng Huang <jchuang@seu.edu.cn>
Assisted-by: Codex:gpt-5.6-luna
---
Changes in v2:
- Add the relevant public mailing lists to Cc; no source changes.

Evidence (v7.2-rc4 KUnit/KASAN oracle under bounded QEMU):
Source: confirmed/hid_lg4ff_short_report_oob_raw_excerpt.log

[    2.638792] KTAP version 1
[    2.638888] 1..1
[    2.641100]     KTAP version 1
[    2.641235]     # Subtest: hid-lg4ff-exploration
[    2.641784]     # module: hid_logitech
[    2.641962]     1..1
[    2.644581] ==================================================================
[    2.645008] BUG: KASAN: slab-out-of-bounds in lg4ff_raw_event+0x2fd/0x410
[    2.645369] Read of size 1 at addr ffff88800229fc63 by task kunit_try_catch/67
[    2.645369] 
[    2.645369] CPU: 1 UID: 0 PID: 67 Comm: kunit_try_catch Tainted: G                 N  7.2.0-rc4-dirty #3 PREEMPT(full) 
[    2.645369] Tainted: [N]=TEST
[    2.645369] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[    2.645369] Call Trace:
[    2.645369]  <TASK>
[    2.645369]  dump_stack_lvl+0x53/0x70
[    2.645369]  print_report+0xd0/0x630
[    2.645369]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
[    2.645369]  ? lg4ff_raw_event+0x2fd/0x410
[    2.645369]  kasan_report+0xe5/0x120
[    2.645369]  ? lg4ff_raw_event+0x2fd/0x410
[    2.645369]  lg4ff_raw_event+0x2fd/0x410
[    2.645369]  lg4ff_short_report_oob_test+0x14e/0x250

 drivers/hid/hid-lg4ff.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c
index e901fdb7d..62f99a932 100644
--- a/drivers/hid/hid-lg4ff.c
+++ b/drivers/hid/hid-lg4ff.c
@@ -336,6 +336,8 @@ int lg4ff_raw_event(struct hid_device *hdev, struct hid_report *report,
 	if (entry->wdata.combine) {
 		switch (entry->wdata.product_id) {
 		case USB_DEVICE_ID_LOGITECH_WHEEL:
+			if (size < 7)
+				return 0;
 			rd[5] = rd[3];
 			rd[6] = 0x7F;
 			return 1;
@@ -343,10 +345,14 @@ int lg4ff_raw_event(struct hid_device *hdev, struct hid_report *report,
 		case USB_DEVICE_ID_LOGITECH_WINGMAN_FFG:
 		case USB_DEVICE_ID_LOGITECH_MOMO_WHEEL:
 		case USB_DEVICE_ID_LOGITECH_MOMO_WHEEL2:
+			if (size < 6)
+				return 0;
 			rd[4] = rd[3];
 			rd[5] = 0x7F;
 			return 1;
 		case USB_DEVICE_ID_LOGITECH_DFP_WHEEL:
+			if (size < 7)
+				return 0;
 			rd[5] = rd[4];
 			rd[6] = 0x7F;
 			return 1;
@@ -366,6 +372,8 @@ int lg4ff_raw_event(struct hid_device *hdev, struct hid_report *report,
 		}
 
 		/* Compute a combined axis when wheel does not supply it */
+		if (size <= offset + 1)
+			return 0;
 		rd[offset] = (0xFF + rd[offset] - rd[offset+1]) >> 1;
 		rd[offset+1] = 0x7F;
 		return 1;
-- 
2.43.0