[Buildroot] [PATCH] package/libusb: apply upstream patch to fix descriptor parsing

[Yann E. MORIN <yann.morin.1998@free.fr>]

John, All,

On 2021-02-19 12:18 +0000, John Keeping spake thusly:
> v1.0.24 of libusb has a bug in the Linux backend where it fails to
> enumerate any device with more than one configuration.  Backport the
> upstream patch which fixes this as otherwise libusb based applications
> are unable to communicate with any devices advertising more than one
> configuration.
> 
> Signed-off-by: John Keeping <john@metanate.com>

Applied to master, thanks.

Regards,
Yann E. MORIN.

> ---
>  ...parsing-of-descriptors-for-multi-con.patch | 62 +++++++++++++++++++
>  1 file changed, 62 insertions(+)
>  create mode 100644 package/libusb/0001-linux_usbfs-Fix-parsing-of-descriptors-for-multi-con.patch
> 
> diff --git a/package/libusb/0001-linux_usbfs-Fix-parsing-of-descriptors-for-multi-con.patch b/package/libusb/0001-linux_usbfs-Fix-parsing-of-descriptors-for-multi-con.patch
> new file mode 100644
> index 0000000000..601b322e54
> --- /dev/null
> +++ b/package/libusb/0001-linux_usbfs-Fix-parsing-of-descriptors-for-multi-con.patch
> @@ -0,0 +1,62 @@
> +From 623e2a995d156e115c91f56a3ec691bdc333df8b Mon Sep 17 00:00:00 2001
> +From: Chris Dickens <christopher.a.dickens@gmail.com>
> +Date: Sun, 13 Dec 2020 15:49:19 -0800
> +Subject: [PATCH 1/1] linux_usbfs: Fix parsing of descriptors for
> + multi-configuration devices
> +
> +Commit e2be556bd2 ("linux_usbfs: Parse config descriptors during device
> +initialization") introduced a regression for devices with multiple
> +configurations. The logic that verifies the reported length of the
> +configuration descriptors failed to count the length of the
> +configuration descriptor itself and would truncate the actual length by
> +9 bytes, leading to a parsing error for subsequent descriptors.
> +
> +Closes #825
> +
> +Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>
> +(cherry picked from commit f6d2cb561402c3b6d3627c0eb89e009b503d9067)
> +Signed-off-by: John Keeping <john@metanate.com>
> +---
> + libusb/os/linux_usbfs.c | 12 ++++++++----
> + 1 file changed, 8 insertions(+), 4 deletions(-)
> +
> +diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
> +index fb2ed53..4d2dc8d 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;
> +-- 
> +2.30.1
> +
> -- 
> 2.30.1
> 
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