2019-07-29 09:17:29

by Jia-Ju Bai

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 <[email protected]>
---
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

2019-08-07 20:18:07

by Bin Liu

Subject: Re: [PATCH] usb: musb: Fix a possible null-pointer dereference in musb_handle_intr_connect()

On Mon, Jul 29, 2019 at 05:04:28PM +0800, Jia-Ju Bai wrote:
> 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 <[email protected]>

Applied. Thanks.

-Bin.