usb: f_fs: Force Reserved1=1 in OS_DESC_EXT_COMPAT
The specification says that the Reserved1 field in OS_DESC_EXT_COMPAT must have the value "1", but when this feature was first implemented we rejected any non-zero values. This was adjusted to accept all non-zero values (while now rejecting zero) in commit53642399aa
("usb: gadget: f_fs: Fix wrong check on reserved1 of OS_DESC_EXT_COMPAT"), but that breaks any userspace programs that worked previously by returning EINVAL when Reserved1 == 0 which was previously the only value that succeeded! If we just set the field to "1" ourselves, both old and new userspace programs continue to work correctly and, as a bonus, old programs are now compliant with the specification without having to fix anything themselves. Fixes:53642399aa
("usb: gadget: f_fs: Fix wrong check on reserved1 of OS_DESC_EXT_COMPAT") Cc: <stable@vger.kernel.org> Signed-off-by: John Keeping <john@metanate.com> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
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@ -2282,9 +2282,18 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
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int i;
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if (len < sizeof(*d) ||
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d->bFirstInterfaceNumber >= ffs->interfaces_count ||
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!d->Reserved1)
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d->bFirstInterfaceNumber >= ffs->interfaces_count)
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return -EINVAL;
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if (d->Reserved1 != 1) {
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/*
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* According to the spec, Reserved1 must be set to 1
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* but older kernels incorrectly rejected non-zero
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* values. We fix it here to avoid returning EINVAL
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* in response to values we used to accept.
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*/
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pr_debug("usb_ext_compat_desc::Reserved1 forced to 1\n");
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d->Reserved1 = 1;
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}
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for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i)
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if (d->Reserved2[i])
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return -EINVAL;
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