FAILED: patch "[PATCH] usb: dwc3: gadget: Fix looping of queued SG entries" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-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 <[email protected]>.

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-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x b7fc65f5141c24785dc8c19249ca4efcf71b3524
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024120326-tactful-stash-66fd@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From b7fc65f5141c24785dc8c19249ca4efcf71b3524 Mon Sep 17 00:00:00 2001
From: Thinh Nguyen <[email protected]>
Date: Thu, 14 Nov 2024 01:02:18 +0000
Subject: [PATCH] usb: dwc3: gadget: Fix looping of queued SG entries

The dwc3_request->num_queued_sgs is decremented on completion. If a partially completed request is handled, then the dwc3_request->num_queued_sgs no longer reflects the total number of num_queued_sgs (it would be cleared).

Correctly check the number of request SG entries remained to be prepare and queued. Failure to do this may cause null pointer dereference when accessing non-existent SG entry.

index 38c3769a6c48..3a5a0d8be33c 100644
@@ -1470,8 +1470,8 @@ static int dwc3_prepare_trbs_sg(struct dwc3_ep *dep,
 	struct scatterlist *s;
 	int		i;
 	unsigned int length = req->request.length;
-	unsigned int remaining = req->request.num_mapped_sgs
-		- req->num_queued_sgs;
+	unsigned int remaining = req->num_pending_sgs;
+	unsigned int num_queued_sgs = req->request.num_mapped_sgs - remaining;
 	unsigned int num_trbs = req->num_trbs;
 	bool needs_extra_trb = dwc3_needs_extra_trb(dep, req);
 

@@ -1479,7 +1479,7 @@ static int dwc3_prepare_trbs_sg(struct dwc3_ep *dep,
 	 * If we resume preparing the request, then get the remaining length of
 	 * the request and resume where we left off.
 	 */
-	for_each_sg(req->request.sg, s, req->num_queued_sgs, i)
+	for_each_sg(req->request.sg, s, num_queued_sgs, i)
 		length -= sg_dma_len(s);
 
 	for_each_sg(sg, s, remaining, i) {