diff options
| author | John Keeping | 2017-11-27 18:15:40 +0000 |
|---|---|---|
| committer | Felipe Balbi | 2017-11-28 13:05:31 +0200 |
| commit | a3acc696085e112733d191a77b106e67a4fa110b (patch) | |
| tree | 149aa791fe110d309dfcba8db474c2b74e0ed3ca /drivers/usb | |
| parent | a4f0927ef588cf62bb864707261482c874352942 (diff) | |
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 commit 53642399aa71 ("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: 53642399aa71 ("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>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/gadget/function/f_fs.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 9aa457b53e01..b6cf5ab5a0a1 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -2282,9 +2282,18 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type, int i; if (len < sizeof(*d) || - d->bFirstInterfaceNumber >= ffs->interfaces_count || - !d->Reserved1) + d->bFirstInterfaceNumber >= ffs->interfaces_count) return -EINVAL; + if (d->Reserved1 != 1) { + /* + * According to the spec, Reserved1 must be set to 1 + * but older kernels incorrectly rejected non-zero + * values. We fix it here to avoid returning EINVAL + * in response to values we used to accept. + */ + pr_debug("usb_ext_compat_desc::Reserved1 forced to 1\n"); + d->Reserved1 = 1; + } for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i) if (d->Reserved2[i]) return -EINVAL; |