linux-kernel - [PATCH] usb: musb: Fix a possible null-pointer dereference in musb_handle_intr

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Date:   Mon, 29 Jul 2019 17:04:28 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     b-liu@...com, gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] usb: musb: Fix a possible null-pointer dereference in musb_handle_intr_connect()

In musb_handle_intr_connect(), there is an if statement on line 783 to
check whether musb->hcd is NULL:
    if (musb->hcd)

When musb->hcd is NULL, it is used on line 797:
    musb_host_poke_root_hub(musb);
        if (musb->hcd->status_urb)

Thus, a possible null-pointer dereference may occur.

To fix this bug, musb->hcd is checked before calling
musb_host_poke_root_hub().

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/usb/musb/musb_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 9f5a4819a744..329ff52f8167 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -794,7 +794,8 @@ static void musb_handle_intr_connect(struct musb *musb, u8 devctl, u8 int_usb)
 		break;
 	}
 
-	musb_host_poke_root_hub(musb);
+	if (musb->hcd)
+		musb_host_poke_root_hub(musb);
 
 	musb_dbg(musb, "CONNECT (%s) devctl %02x",
 			usb_otg_state_string(musb->xceiv->otg->state), devctl);
-- 
2.17.0