From f6d2cb561402c3b6d3627c0eb89e009b503d9067 Sun 17 01 11:38:45 2021
From: Simon Vogl <simon.vogl@gmx.net>
Date: Sun, 17 Jan 2021 11:38:45 UTC
Subject: [PATCH] Fix USB Device enumeration

This patch fixes a regression introduced in libusb 1.0.24 that prevents certain devices like smartphones from being detected.
 
diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index fb2ed53a..4d2dc8d6 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -641,7 +641,12 @@ static int seek_to_next_config(struct libusb_context *ctx,
 	uint8_t *buffer, size_t len)
 {
 	struct usbi_descriptor_header *header;
-	int offset = 0;
+	int offset;
+
+	/* Start seeking past the config descriptor */
+	offset = LIBUSB_DT_CONFIG_SIZE;
+	buffer += LIBUSB_DT_CONFIG_SIZE;
+	len -= LIBUSB_DT_CONFIG_SIZE;
 
 	while (len > 0) {
 		if (len < 2) {
@@ -718,7 +723,7 @@ static int parse_config_descriptors(struct libusb_device *dev)
 		}
 
 		if (priv->sysfs_dir) {
-			 /*
+			/*
 			 * In sysfs wTotalLength is ignored, instead the kernel returns a
 			 * config descriptor with verified bLength fields, with descriptors
 			 * with an invalid bLength removed.
@@ -727,8 +732,7 @@ static int parse_config_descriptors(struct libusb_device *dev)
 			int offset;
 
 			if (num_configs > 1 && idx < num_configs - 1) {
-				offset = seek_to_next_config(ctx, buffer + LIBUSB_DT_CONFIG_SIZE,
-							     remaining - LIBUSB_DT_CONFIG_SIZE);
+				offset = seek_to_next_config(ctx, buffer, remaining);
 				if (offset < 0)
 					return offset;
 				sysfs_config_len = (uint16_t)offset;