FAILED: patch "[PATCH] usb: free iso schedules on failed submit" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x b9399d25fbb34a05bbe76eeedd730f62ff2670e9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026071434-steed-earmuff-b781@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b9399d25fbb34a05bbe76eeedd730f62ff2670e9 Mon Sep 17 00:00:00 2001
From: Dawei Feng <dawei.feng@seu.edu.cn>
Date: Tue, 30 Jun 2026 15:14:19 +0800
Subject: [PATCH] usb: free iso schedules on failed submit

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 <stable@kernel.org>
Signed-off-by: Dawei Feng <dawei.feng@seu.edu.cn>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://patch.msgid.link/20260630071419.349161-1-dawei.feng@seu.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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;