[PATCH] net: hinic: fix mailbox segment buffer overflow

[Aamir Ahmed]

check_mbox_seq_id_and_seg_len() validates that seq_id does not
exceed SEQ_ID_MAX_VAL (42) and seg_len does not exceed
MBOX_SEG_LEN (48).  However, this allows the last segment
(seq_id=42) to carry a full 48-byte payload, writing to offset
42*48=2016 for 48 bytes (ending at byte 2064).  The receive
buffer is only MBOX_MAX_BUF_SZ (2048) bytes, resulting in a
16-byte heap buffer overflow.

The hinic3 driver already handles this correctly by defining
MBOX_LAST_SEG_MAX_LEN and rejecting the last segment when it
exceeds the remaining buffer space.  Apply the same fix to the
hinic driver.

Fixes: a425b6e1c69b ("hinic: add mailbox function support")
Signed-off-by: Aamir Ahmed <elb12345@xxxxxxxxxxxxx>
---
 drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c b/drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c
index 2784127327e6..6e67a6c9578e 100644
--- a/drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c
+++ b/drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c
@@ -128,6 +128,7 @@ enum hinic_mbox_tx_status {
 
 #define SEQ_ID_START_VAL			0
 #define SEQ_ID_MAX_VAL				42
+#define MBOX_LAST_SEG_MAX_LEN			(MBOX_MAX_BUF_SZ - SEQ_ID_MAX_VAL * MBOX_SEG_LEN)
 
 #define NO_DMA_ATTRIBUTE_VAL			0
 
@@ -372,7 +373,8 @@ recv_pf_from_vf_mbox_handler(struct hinic_mbox_func_to_func *func_to_func,
 static bool check_mbox_seq_id_and_seg_len(struct hinic_recv_mbox *recv_mbox,
 					  u8 seq_id, u8 seg_len)
 {
-	if (seq_id > SEQ_ID_MAX_VAL || seg_len > MBOX_SEG_LEN)
+	if (seq_id > SEQ_ID_MAX_VAL || seg_len > MBOX_SEG_LEN ||
+	    (seq_id == SEQ_ID_MAX_VAL && seg_len > MBOX_LAST_SEG_MAX_LEN))
 		return false;
 
 	if (seq_id == 0) {
-- 
2.43.0