[PATCH v2] usb: free iso schedules on failed submit

[Dawei Feng]

EHCI and FOTG210 isochronous submits build an ehci_iso_sched before
linking the URB to the endpoint queue, and keep the staged schedule in
urb->hcpriv until iso_stream_schedule() and the link helpers consume it.
If the controller is no longer accessible, or usb_hcd_link_urb_to_ep()
fails, submit jumps to done_not_linked before that handoff happens and
leaks the staged schedule still attached to urb->hcpriv.

Free the staged schedule from done_not_linked when submit fails before
the URB is linked and clear urb->hcpriv after the free.

The bug was first flagged by an experimental analysis tool we are
developing for kernel memory-management bugs while analyzing
v6.13-rc1. The tool is still under development and is not yet publicly
available. Manual inspection confirms that the bug is still
present in v7.1.1.

An x86_64 allyesconfig build showed no new warnings. As we do not have an
EHCI host controller with a USB isochronous device to test with, no
runtime testing was able to be performed.

Fixes: 8de98402652c ("[PATCH] USB: Fix USB suspend/resume crasher (#2)")
Fixes: e9df41c5c589 ("USB: make HCDs responsible for managing endpoint queues")
Fixes: 7d50195f6c50 ("usb: host: Faraday fotg210-hcd driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dawei Feng <dawei.feng@xxxxxxxxxx>
---
Changes in v2:
- Move negative iso_stream_schedule() cleanup to the submit failure path.
- Clear urb->hcpriv after iso_stream_schedule() frees the schedule for an
  immediately completed EHCI URB.

 drivers/usb/fotg210/fotg210-hcd.c |  6 ++++--
 drivers/usb/host/ehci-sched.c     | 11 +++++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/fotg210/fotg210-hcd.c b/drivers/usb/fotg210/fotg210-hcd.c
index 1a48329a4e08..956be5b56510 100644
--- a/drivers/usb/fotg210/fotg210-hcd.c
+++ b/drivers/usb/fotg210/fotg210-hcd.c
@@ -4267,8 +4267,6 @@ static int iso_stream_schedule(struct fotg210_hcd *fotg210, struct urb *urb,
 	return 0;
 
 fail:
-	iso_sched_free(stream, sched);
-	urb->hcpriv = NULL;
 	return status;
 }
 
@@ -4562,6 +4560,10 @@ static int itd_submit(struct fotg210_hcd *fotg210, struct urb *urb,
 	else
 		usb_hcd_unlink_urb_from_ep(fotg210_to_hcd(fotg210), urb);
 done_not_linked:
+	if (status < 0) {
+		iso_sched_free(stream, urb->hcpriv);
+		urb->hcpriv = NULL;
+	}
 	spin_unlock_irqrestore(&fotg210->lock, flags);
 done:
 	return status;
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index a241337c9af8..57d07d1c2dfa 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1623,6 +1623,7 @@ iso_stream_schedule(
 			status = 1;	/* and give it back immediately */
 			iso_sched_free(stream, sched);
 			sched = NULL;
+			urb->hcpriv = NULL;
 		}
 	}
 	urb->error_count = skip / period;
@@ -1653,8 +1654,6 @@ iso_stream_schedule(
 	return status;
 
  fail:
-	iso_sched_free(stream, sched);
-	urb->hcpriv = NULL;
 	return status;
 }
 
@@ -1966,6 +1965,10 @@ static int itd_submit(struct ehci_hcd *ehci, struct urb *urb,
 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 	}
  done_not_linked:
+	if (status < 0) {
+		iso_sched_free(stream, urb->hcpriv);
+		urb->hcpriv = NULL;
+	}
 	spin_unlock_irqrestore(&ehci->lock, flags);
  done:
 	return status;
@@ -2343,6 +2346,10 @@ static int sitd_submit(struct ehci_hcd *ehci, struct urb *urb,
 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 	}
  done_not_linked:
+	if (status < 0) {
+		iso_sched_free(stream, urb->hcpriv);
+		urb->hcpriv = NULL;
+	}
 	spin_unlock_irqrestore(&ehci->lock, flags);
  done:
 	return status;
-- 
2.34.1