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Subject[PATCH] usb: gadget: aspeed: fix buffer overflow
Date
From: Henry Tian <tianxiaofeng@bytedance.com>

In ast_vhub_epn_handle_ack() when the received data length exceeds the
buffer, it does not check the case and just copies to req.buf and cause
a buffer overflow, kernel oops on this case.

This issue could be reproduced on a BMC with an OS that enables the
lan over USB:
1. In OS, enable the usb eth dev, verify it pings the BMC OK;
2. In OS, set the usb dev mtu to 2000. (Default is 1500);
3. In OS, ping the BMC with `-s 2000` argument.

The BMC kernel will get oops with below logs:

skbuff: skb_over_panic: text:8058e098 len:2048 put:2048 head:84c678a0 data:84c678c2 tail:0x84c680c2 end:0x84c67f00 dev:usb0
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:113!
Internal error: Oops - BUG: 0 [#1] ARM
CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.69-c9fb275-dirty-d1e579a #1
Hardware name: Generic DT based system
PC is at skb_panic+0x60/0x6c
LR is at irq_work_queue+0x6c/0x94

Fix the issue by checking the length and set `-EOVERFLOW`.

Tested: Verify the BMC kernel does not get oops in the above case, and
the usb ethernet gets RX packets errors instead.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Signed-off-by: Henry Tian <tianxiaofeng@bytedance.com>
---
drivers/usb/gadget/udc/aspeed-vhub/core.c | 2 +-
drivers/usb/gadget/udc/aspeed-vhub/epn.c | 16 ++++++++++++----
2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
index 7a635c499777..ac3ca24f8b04 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
@@ -37,7 +37,7 @@ void ast_vhub_done(struct ast_vhub_ep *ep, struct ast_vhub_req *req,

list_del_init(&req->queue);

- if (req->req.status == -EINPROGRESS)
+ if ((req->req.status == -EINPROGRESS) || (status == -EOVERFLOW))
req->req.status = status;

if (req->req.dma) {
diff --git a/drivers/usb/gadget/udc/aspeed-vhub/epn.c b/drivers/usb/gadget/udc/aspeed-vhub/epn.c
index b5252880b389..56e55472daa1 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/epn.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/epn.c
@@ -84,6 +84,7 @@ static void ast_vhub_epn_handle_ack(struct ast_vhub_ep *ep)
{
struct ast_vhub_req *req;
unsigned int len;
+ int status = 0;
u32 stat;

/* Read EP status */
@@ -119,9 +120,15 @@ static void ast_vhub_epn_handle_ack(struct ast_vhub_ep *ep)
len = VHUB_EP_DMA_TX_SIZE(stat);

/* If not using DMA, copy data out if needed */
- if (!req->req.dma && !ep->epn.is_in && len)
- memcpy(req->req.buf + req->req.actual, ep->buf, len);
-
+ if (!req->req.dma && !ep->epn.is_in && len) {
+ if (req->req.actual + len > req->req.length) {
+ req->last_desc = 1;
+ status = -EOVERFLOW;
+ goto done;
+ } else {
+ memcpy(req->req.buf + req->req.actual, ep->buf, len);
+ }
+ }
/* Adjust size */
req->req.actual += len;

@@ -129,9 +136,10 @@ static void ast_vhub_epn_handle_ack(struct ast_vhub_ep *ep)
if (len < ep->ep.maxpacket)
req->last_desc = 1;

+done:
/* That's it ? complete the request and pick a new one */
if (req->last_desc >= 0) {
- ast_vhub_done(ep, req, 0);
+ ast_vhub_done(ep, req, status);
req = list_first_entry_or_null(&ep->queue, struct ast_vhub_req,
queue);

--
2.11.0
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