2022-02-14 14:48:33

by Jung Daehwan

Subject: [PATCH v2 2/2] usb: dwc3: Prevent cleanup cancelled requests at the same time.

We added cleanup cancelled requests when ep cmd timeout on ep dequeue
because there's no complete interrupt then. But, we find out new case
that complete interrupt comes up later. list_for_each_entry_safe is
used when cleanup cancelled requests and it has vulnerabilty on multi-core
environment. dwc3_gadget_giveback unlocks dwc->lock temporarily and other
core(ISR) can get lock and try to cleanup them again. It could cause
list_del corruption and we use DWC3_EP_END_TRANSFER_PENDING to prevent it.

1. MTP server cancels -> ep dequeue -> ep cmd timeout(END_TRANSFER)
-> cleanup cancelled requests -> dwc3_gadget_giveback ->
list_del -> release lock temporarily
2. Complete with END_TRANSFER -> ISR(dwc3_gadget_endpoint_command_complete)
gets lock -> cleanup cancelled requests -> dwc3_gadget_giveback
-> list_del
3. MTP server process gets lock again
-> tries to access POISON list(list_del corruption)

[2: MtpServer: 5032] dwc3 10b00000.dwc3: request cancelled
with wrong reason:5
[2: MtpServer: 5032] list_del corruption,
ffffff88b6963968->next is LIST_POISON1 (dead000000000100)

Signed-off-by: Daehwan Jung <[email protected]>
---
drivers/usb/dwc3/gadget.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 3ad3bc5813ca..bac3814894e2 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2046,8 +2046,11 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,

/* If ep cmd fails, then force to giveback cancelled requests here */
if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING)) {
- dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
+ dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
dwc3_gadget_ep_cleanup_cancelled_requests(dep);
+
+ dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
+ dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
}

dep->flags &= ~DWC3_EP_WAIT_TRANSFER_COMPLETE;
@@ -3426,9 +3429,11 @@ static void dwc3_gadget_endpoint_command_complete(struct dwc3_ep *dep,
if (dep->stream_capable)
dep->flags |= DWC3_EP_IGNORE_NEXT_NOSTREAM;

+ if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
+ dwc3_gadget_ep_cleanup_cancelled_requests(dep);
+
dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
- dwc3_gadget_ep_cleanup_cancelled_requests(dep);

if (dep->flags & DWC3_EP_PENDING_CLEAR_STALL) {
struct dwc3 *dwc = dep->dwc;
--
2.31.1

2022-02-14 18:58:43

by Greg Kroah-Hartman

Subject: Re: [PATCH v2 2/2] usb: dwc3: Prevent cleanup cancelled requests at the same time.

On Mon, Feb 14, 2022 at 08:08:53PM +0900, Daehwan Jung wrote:
> We added cleanup cancelled requests when ep cmd timeout on ep dequeue
> because there's no complete interrupt then. But, we find out new case
> that complete interrupt comes up later. list_for_each_entry_safe is
> used when cleanup cancelled requests and it has vulnerabilty on multi-core
> environment. dwc3_gadget_giveback unlocks dwc->lock temporarily and other
> core(ISR) can get lock and try to cleanup them again. It could cause
> list_del corruption and we use DWC3_EP_END_TRANSFER_PENDING to prevent it.
>
> 1. MTP server cancels -> ep dequeue -> ep cmd timeout(END_TRANSFER)
> -> cleanup cancelled requests -> dwc3_gadget_giveback ->
> list_del -> release lock temporarily
> 2. Complete with END_TRANSFER -> ISR(dwc3_gadget_endpoint_command_complete)
> gets lock -> cleanup cancelled requests -> dwc3_gadget_giveback
> -> list_del
> 3. MTP server process gets lock again
> -> tries to access POISON list(list_del corruption)
>
> [2: MtpServer: 5032] dwc3 10b00000.dwc3: request cancelled
> with wrong reason:5
> [2: MtpServer: 5032] list_del corruption,
> ffffff88b6963968->next is LIST_POISON1 (dead000000000100)
>
> Signed-off-by: Daehwan Jung <[email protected]>
> ---
> drivers/usb/dwc3/gadget.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)

What commit id does this fix?

thanks,

greg k-h