[PATCH v2] hw/net/can: sja1000 fix buff2frame_bas and buff2frame_pel when dlc is out of std CAN 8 bytes

[Pavel Pisa <pisa@cmp.felk.cvut.cz>]

Problem reported by openEuler fuzz-sig group.

The buff2frame_bas function (hw\net\can\can_sja1000.c)
infoleak(qemu5.x~qemu6.x) or stack-overflow(qemu 4.x).

Reported-by: Qiang Ning <ningqiang1@huawei.com>
Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
---
 hw/net/can/can_sja1000.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/hw/net/can/can_sja1000.c b/hw/net/can/can_sja1000.c
index 42d2f99dfb..34eea684ce 100644
--- a/hw/net/can/can_sja1000.c
+++ b/hw/net/can/can_sja1000.c
@@ -275,6 +275,10 @@ static void buff2frame_pel(const uint8_t *buff, qemu_can_frame *frame)
     }
     frame->can_dlc = buff[0] & 0x0f;
 
+    if (frame->can_dlc > 8) {
+        frame->can_dlc = 8;
+    }
+
     if (buff[0] & 0x80) { /* Extended */
         frame->can_id |= QEMU_CAN_EFF_FLAG;
         frame->can_id |= buff[1] << 21; /* ID.28~ID.21 */
@@ -311,6 +315,10 @@ static void buff2frame_bas(const uint8_t *buff, qemu_can_frame *frame)
     }
     frame->can_dlc = buff[1] & 0x0f;
 
+    if (frame->can_dlc > 8) {
+        frame->can_dlc = 8;
+    }
+
     for (i = 0; i < frame->can_dlc; i++) {
         frame->data[i] = buff[2 + i];
     }
-- 
2.20.1