* [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases
@ 2026-03-17 4:22 Cássio Gabriel
2026-03-17 9:03 ` Takashi Iwai
0 siblings, 1 reply; 5+ messages in thread
From: Cássio Gabriel @ 2026-03-17 4:22 UTC (permalink / raw)
To: Takashi Iwai
Cc: Jaroslav Kysela, Greg Kroah-Hartman, linux-sound, linux-usb,
linux-kernel, Cássio Gabriel
get_alias_quirk() resolves a quirk for an aliased USB ID by scanning
usb_audio_ids[], but it currently checks only the vendor/product pair.
This is weak for quirk table entries that also depend on additional
USB_DEVICE_ID match fields, such as device or interface class,
subclass, protocol, interface number, or bcdDevice range.
Rework the alias lookup so that it still uses the aliased vid:pid as
the initial lookup key, but validates the remaining match_flags
constraints of each candidate entry against the real device and
interface descriptors before returning the quirk.
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
---
Changes in v2:
- drop the temporary usb_device_id reconstruction approach
- validate only the remaining match_flags explicitly
- pass struct usb_interface * to get_alias_quirk()
- Link to v1: https://lore.kernel.org/r/20260314-alsa-usb-fix-quirk-alias-v1-1-3269998f7ada@gmail.com
---
sound/usb/card.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 64 insertions(+), 8 deletions(-)
diff --git a/sound/usb/card.c b/sound/usb/card.c
index fd81f32a66fb..153085a77d43 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -864,21 +864,77 @@ static void find_last_interface(struct snd_usb_audio *chip)
usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface);
}
+/*
+ * Match aliased vid:pid first, then validate remaining fields against
+ * the real device and interface descriptors.
+ */
+static bool snd_usb_match_alias_entry(struct usb_interface *intf,
+ const struct usb_device_id *id,
+ u32 alias_id)
+{
+ struct usb_device *dev = interface_to_usbdev(intf);
+ const struct usb_host_interface *alt = intf->cur_altsetting;
+ const struct usb_interface_descriptor *intfd = &alt->desc;
+ const struct usb_device_descriptor *devd = &dev->descriptor;
+ u16 bcd = le16_to_cpu(devd->bcdDevice);
+
+ /* Match aliased vendor/product */
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
+ id->idVendor != USB_ID_VENDOR(alias_id))
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
+ id->idProduct != USB_ID_PRODUCT(alias_id))
+ return false;
+ /* Match real device descriptor constraints */
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
+ bcd < id->bcdDevice_lo)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
+ bcd > id->bcdDevice_hi)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
+ devd->bDeviceClass != id->bDeviceClass)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
+ devd->bDeviceSubClass != id->bDeviceSubClass)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
+ devd->bDeviceProtocol != id->bDeviceProtocol)
+ return false;
+ /* Match real interface descriptor constraints */
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
+ intfd->bInterfaceClass != id->bInterfaceClass)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
+ intfd->bInterfaceSubClass != id->bInterfaceSubClass)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
+ intfd->bInterfaceProtocol != id->bInterfaceProtocol)
+ return false;
+ if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER) &&
+ intfd->bInterfaceNumber != id->bInterfaceNumber)
+ return false;
+
+ return true;
+}
+
/* look for the corresponding quirk */
static const struct snd_usb_audio_quirk *
-get_alias_quirk(struct usb_device *dev, unsigned int id)
+get_alias_quirk(struct usb_interface *intf, unsigned int id)
{
const struct usb_device_id *p;
for (p = usb_audio_ids; p->match_flags; p++) {
- /* FIXME: this checks only vendor:product pair in the list */
- if ((p->match_flags & USB_DEVICE_ID_MATCH_DEVICE) ==
- USB_DEVICE_ID_MATCH_DEVICE &&
- p->idVendor == USB_ID_VENDOR(id) &&
- p->idProduct == USB_ID_PRODUCT(id))
+ /*
+ * Alias lookup only considers entries anchored on vid:pid.
+ * Additional device/interface constraints are validated separately.
+ */
+ if ((p->match_flags & USB_DEVICE_ID_MATCH_DEVICE) !=
+ USB_DEVICE_ID_MATCH_DEVICE)
+ continue;
+ if (snd_usb_match_alias_entry(intf, p, id))
return (const struct snd_usb_audio_quirk *)p->driver_info;
}
-
return NULL;
}
@@ -927,7 +983,7 @@ static int usb_audio_probe(struct usb_interface *intf,
id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
le16_to_cpu(dev->descriptor.idProduct));
if (get_alias_id(dev, &id))
- quirk = get_alias_quirk(dev, id);
+ quirk = get_alias_quirk(intf, id);
if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
return -ENXIO;
if (quirk && quirk->ifnum == QUIRK_NODEV_INTERFACE)
---
base-commit: dcf16b3bb87632a80ef344433980539c2785dfd4
change-id: 20260313-alsa-usb-fix-quirk-alias-e9c8300ba836
Best regards,
--
Cássio Gabriel <cassiogabrielcontato@gmail.com>
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases
2026-03-17 4:22 [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases Cássio Gabriel
@ 2026-03-17 9:03 ` Takashi Iwai
2026-03-17 17:35 ` Cássio Gabriel
0 siblings, 1 reply; 5+ messages in thread
From: Takashi Iwai @ 2026-03-17 9:03 UTC (permalink / raw)
To: Cássio Gabriel
Cc: Takashi Iwai, Jaroslav Kysela, Greg Kroah-Hartman, linux-sound,
linux-usb, linux-kernel
On Tue, 17 Mar 2026 05:22:04 +0100,
Cássio Gabriel wrote:
>
> get_alias_quirk() resolves a quirk for an aliased USB ID by scanning
> usb_audio_ids[], but it currently checks only the vendor/product pair.
>
> This is weak for quirk table entries that also depend on additional
> USB_DEVICE_ID match fields, such as device or interface class,
> subclass, protocol, interface number, or bcdDevice range.
>
> Rework the alias lookup so that it still uses the aliased vid:pid as
> the initial lookup key, but validates the remaining match_flags
> constraints of each candidate entry against the real device and
> interface descriptors before returning the quirk.
>
> Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
> ---
> Changes in v2:
> - drop the temporary usb_device_id reconstruction approach
> - validate only the remaining match_flags explicitly
> - pass struct usb_interface * to get_alias_quirk()
> - Link to v1: https://lore.kernel.org/r/20260314-alsa-usb-fix-quirk-alias-v1-1-3269998f7ada@gmail.com
> ---
> sound/usb/card.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 64 insertions(+), 8 deletions(-)
>
> diff --git a/sound/usb/card.c b/sound/usb/card.c
> index fd81f32a66fb..153085a77d43 100644
> --- a/sound/usb/card.c
> +++ b/sound/usb/card.c
> @@ -864,21 +864,77 @@ static void find_last_interface(struct snd_usb_audio *chip)
> usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface);
> }
>
> +/*
> + * Match aliased vid:pid first, then validate remaining fields against
> + * the real device and interface descriptors.
> + */
> +static bool snd_usb_match_alias_entry(struct usb_interface *intf,
> + const struct usb_device_id *id,
> + u32 alias_id)
> +{
> + struct usb_device *dev = interface_to_usbdev(intf);
> + const struct usb_host_interface *alt = intf->cur_altsetting;
> + const struct usb_interface_descriptor *intfd = &alt->desc;
> + const struct usb_device_descriptor *devd = &dev->descriptor;
> + u16 bcd = le16_to_cpu(devd->bcdDevice);
> +
> + /* Match aliased vendor/product */
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
> + id->idVendor != USB_ID_VENDOR(alias_id))
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
> + id->idProduct != USB_ID_PRODUCT(alias_id))
> + return false;
> + /* Match real device descriptor constraints */
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
> + bcd < id->bcdDevice_lo)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
> + bcd > id->bcdDevice_hi)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
> + devd->bDeviceClass != id->bDeviceClass)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
> + devd->bDeviceSubClass != id->bDeviceSubClass)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
> + devd->bDeviceProtocol != id->bDeviceProtocol)
> + return false;
> + /* Match real interface descriptor constraints */
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
> + intfd->bInterfaceClass != id->bInterfaceClass)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
> + intfd->bInterfaceSubClass != id->bInterfaceSubClass)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
> + intfd->bInterfaceProtocol != id->bInterfaceProtocol)
> + return false;
> + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER) &&
> + intfd->bInterfaceNumber != id->bInterfaceNumber)
> + return false;
> +
> + return true;
> +}
Hrm, it became larger than I wished.
You compared with another implementation and decided to choose this
version?
An alternative would be to have a copy of usb_device_id like your
previous version, and clear match_flags bits with
~USB_DEVICE_ID_MATCH_DEVICE. If match_flags becomes 0, it passes.
Otherwise call usb_match_one_id().
thanks,
Takashi
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases
2026-03-17 9:03 ` Takashi Iwai
@ 2026-03-17 17:35 ` Cássio Gabriel
2026-03-18 7:19 ` Takashi Iwai
0 siblings, 1 reply; 5+ messages in thread
From: Cássio Gabriel @ 2026-03-17 17:35 UTC (permalink / raw)
To: Takashi Iwai
Cc: Takashi Iwai, Jaroslav Kysela, Greg Kroah-Hartman, linux-sound,
linux-usb, linux-kernel
On Tue, Mar 17, 2026 at 10:03:10AM +0100, Takashi Iwai wrote:
> On Tue, 17 Mar 2026 05:22:04 +0100,
> Cássio Gabriel wrote:
> >
> > get_alias_quirk() resolves a quirk for an aliased USB ID by scanning
> > usb_audio_ids[], but it currently checks only the vendor/product pair.
> >
> > This is weak for quirk table entries that also depend on additional
> > USB_DEVICE_ID match fields, such as device or interface class,
> > subclass, protocol, interface number, or bcdDevice range.
> >
> > Rework the alias lookup so that it still uses the aliased vid:pid as
> > the initial lookup key, but validates the remaining match_flags
> > constraints of each candidate entry against the real device and
> > interface descriptors before returning the quirk.
> >
> > Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
> > ---
> > Changes in v2:
> > - drop the temporary usb_device_id reconstruction approach
> > - validate only the remaining match_flags explicitly
> > - pass struct usb_interface * to get_alias_quirk()
> > - Link to v1: https://lore.kernel.org/r/20260314-alsa-usb-fix-quirk-alias-v1-1-3269998f7ada@gmail.com
> > ---
> > sound/usb/card.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-------
> > 1 file changed, 64 insertions(+), 8 deletions(-)
> >
> > diff --git a/sound/usb/card.c b/sound/usb/card.c
> > index fd81f32a66fb..153085a77d43 100644
> > --- a/sound/usb/card.c
> > +++ b/sound/usb/card.c
> > @@ -864,21 +864,77 @@ static void find_last_interface(struct snd_usb_audio *chip)
> > usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface);
> > }
> >
> > +/*
> > + * Match aliased vid:pid first, then validate remaining fields against
> > + * the real device and interface descriptors.
> > + */
> > +static bool snd_usb_match_alias_entry(struct usb_interface *intf,
> > + const struct usb_device_id *id,
> > + u32 alias_id)
> > +{
> > + struct usb_device *dev = interface_to_usbdev(intf);
> > + const struct usb_host_interface *alt = intf->cur_altsetting;
> > + const struct usb_interface_descriptor *intfd = &alt->desc;
> > + const struct usb_device_descriptor *devd = &dev->descriptor;
> > + u16 bcd = le16_to_cpu(devd->bcdDevice);
> > +
> > + /* Match aliased vendor/product */
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
> > + id->idVendor != USB_ID_VENDOR(alias_id))
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
> > + id->idProduct != USB_ID_PRODUCT(alias_id))
> > + return false;
> > + /* Match real device descriptor constraints */
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
> > + bcd < id->bcdDevice_lo)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
> > + bcd > id->bcdDevice_hi)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
> > + devd->bDeviceClass != id->bDeviceClass)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
> > + devd->bDeviceSubClass != id->bDeviceSubClass)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
> > + devd->bDeviceProtocol != id->bDeviceProtocol)
> > + return false;
> > + /* Match real interface descriptor constraints */
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
> > + intfd->bInterfaceClass != id->bInterfaceClass)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
> > + intfd->bInterfaceSubClass != id->bInterfaceSubClass)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
> > + intfd->bInterfaceProtocol != id->bInterfaceProtocol)
> > + return false;
> > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER) &&
> > + intfd->bInterfaceNumber != id->bInterfaceNumber)
> > + return false;
> > +
> > + return true;
> > +}
>
> Hrm, it became larger than I wished.
> You compared with another implementation and decided to choose this
> version?
>
Hi,
I went with the explicit matching path in v2 because I wanted to keep
the alias lookup based on the aliased vid:pid while validating the
remaining match_flags against the real descriptors.
> An alternative would be to have a copy of usb_device_id like your
> previous version, and clear match_flags bits with
> ~USB_DEVICE_ID_MATCH_DEVICE. If match_flags becomes 0, it passes.
> Otherwise call usb_match_one_id().
thanks, that makes sense.
What do you think about this approach?
```
static const struct snd_usb_audio_quirk *
get_alias_quirk(struct usb_interface *intf, unsigned int id)
{
const struct usb_device_id *p;
struct usb_device_id match_id;
for (p = usb_audio_ids; p->match_flags; p++) {
if ((p->match_flags & USB_DEVICE_ID_MATCH_DEVICE) !=
USB_DEVICE_ID_MATCH_DEVICE)
continue;
if (p->idVendor != USB_ID_VENDOR(id) ||
p->idProduct != USB_ID_PRODUCT(id))
continue;
match_id = *p;
match_id.match_flags &= ~USB_DEVICE_ID_MATCH_DEVICE;
if (!match_id.match_flags || usb_match_one_id(intf, &match_id))
return (const struct snd_usb_audio_quirk *)
p->driver_info;
}
return NULL;
}
```
Thanks,
Cássio.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases
2026-03-17 17:35 ` Cássio Gabriel
@ 2026-03-18 7:19 ` Takashi Iwai
2026-03-18 12:06 ` Cássio Gabriel
0 siblings, 1 reply; 5+ messages in thread
From: Takashi Iwai @ 2026-03-18 7:19 UTC (permalink / raw)
To: Cássio Gabriel
Cc: Takashi Iwai, Takashi Iwai, Jaroslav Kysela, Greg Kroah-Hartman,
linux-sound, linux-usb, linux-kernel
On Tue, 17 Mar 2026 18:35:16 +0100,
Cássio Gabriel wrote:
>
> On Tue, Mar 17, 2026 at 10:03:10AM +0100, Takashi Iwai wrote:
> > On Tue, 17 Mar 2026 05:22:04 +0100,
> > Cássio Gabriel wrote:
> > >
> > > get_alias_quirk() resolves a quirk for an aliased USB ID by scanning
> > > usb_audio_ids[], but it currently checks only the vendor/product pair.
> > >
> > > This is weak for quirk table entries that also depend on additional
> > > USB_DEVICE_ID match fields, such as device or interface class,
> > > subclass, protocol, interface number, or bcdDevice range.
> > >
> > > Rework the alias lookup so that it still uses the aliased vid:pid as
> > > the initial lookup key, but validates the remaining match_flags
> > > constraints of each candidate entry against the real device and
> > > interface descriptors before returning the quirk.
> > >
> > > Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
> > > ---
> > > Changes in v2:
> > > - drop the temporary usb_device_id reconstruction approach
> > > - validate only the remaining match_flags explicitly
> > > - pass struct usb_interface * to get_alias_quirk()
> > > - Link to v1: https://lore.kernel.org/r/20260314-alsa-usb-fix-quirk-alias-v1-1-3269998f7ada@gmail.com
> > > ---
> > > sound/usb/card.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-------
> > > 1 file changed, 64 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/sound/usb/card.c b/sound/usb/card.c
> > > index fd81f32a66fb..153085a77d43 100644
> > > --- a/sound/usb/card.c
> > > +++ b/sound/usb/card.c
> > > @@ -864,21 +864,77 @@ static void find_last_interface(struct snd_usb_audio *chip)
> > > usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface);
> > > }
> > >
> > > +/*
> > > + * Match aliased vid:pid first, then validate remaining fields against
> > > + * the real device and interface descriptors.
> > > + */
> > > +static bool snd_usb_match_alias_entry(struct usb_interface *intf,
> > > + const struct usb_device_id *id,
> > > + u32 alias_id)
> > > +{
> > > + struct usb_device *dev = interface_to_usbdev(intf);
> > > + const struct usb_host_interface *alt = intf->cur_altsetting;
> > > + const struct usb_interface_descriptor *intfd = &alt->desc;
> > > + const struct usb_device_descriptor *devd = &dev->descriptor;
> > > + u16 bcd = le16_to_cpu(devd->bcdDevice);
> > > +
> > > + /* Match aliased vendor/product */
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
> > > + id->idVendor != USB_ID_VENDOR(alias_id))
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
> > > + id->idProduct != USB_ID_PRODUCT(alias_id))
> > > + return false;
> > > + /* Match real device descriptor constraints */
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
> > > + bcd < id->bcdDevice_lo)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
> > > + bcd > id->bcdDevice_hi)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
> > > + devd->bDeviceClass != id->bDeviceClass)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
> > > + devd->bDeviceSubClass != id->bDeviceSubClass)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
> > > + devd->bDeviceProtocol != id->bDeviceProtocol)
> > > + return false;
> > > + /* Match real interface descriptor constraints */
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
> > > + intfd->bInterfaceClass != id->bInterfaceClass)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
> > > + intfd->bInterfaceSubClass != id->bInterfaceSubClass)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
> > > + intfd->bInterfaceProtocol != id->bInterfaceProtocol)
> > > + return false;
> > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER) &&
> > > + intfd->bInterfaceNumber != id->bInterfaceNumber)
> > > + return false;
> > > +
> > > + return true;
> > > +}
> >
> > Hrm, it became larger than I wished.
> > You compared with another implementation and decided to choose this
> > version?
> >
>
> Hi,
>
> I went with the explicit matching path in v2 because I wanted to keep
> the alias lookup based on the aliased vid:pid while validating the
> remaining match_flags against the real descriptors.
>
> > An alternative would be to have a copy of usb_device_id like your
> > previous version, and clear match_flags bits with
> > ~USB_DEVICE_ID_MATCH_DEVICE. If match_flags becomes 0, it passes.
> > Otherwise call usb_match_one_id().
>
> thanks, that makes sense.
>
> What do you think about this approach?
> ```
> static const struct snd_usb_audio_quirk *
> get_alias_quirk(struct usb_interface *intf, unsigned int id)
> {
> const struct usb_device_id *p;
> struct usb_device_id match_id;
>
> for (p = usb_audio_ids; p->match_flags; p++) {
> if ((p->match_flags & USB_DEVICE_ID_MATCH_DEVICE) !=
> USB_DEVICE_ID_MATCH_DEVICE)
> continue;
>
> if (p->idVendor != USB_ID_VENDOR(id) ||
> p->idProduct != USB_ID_PRODUCT(id))
> continue;
>
> match_id = *p;
> match_id.match_flags &= ~USB_DEVICE_ID_MATCH_DEVICE;
> if (!match_id.match_flags || usb_match_one_id(intf, &match_id))
> return (const struct snd_usb_audio_quirk *)
> p->driver_info;
> }
>
> return NULL;
> }
> ```
Yes, that's what I had in mind.
thanks,
Takashi
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases
2026-03-18 7:19 ` Takashi Iwai
@ 2026-03-18 12:06 ` Cássio Gabriel
0 siblings, 0 replies; 5+ messages in thread
From: Cássio Gabriel @ 2026-03-18 12:06 UTC (permalink / raw)
To: Takashi Iwai
Cc: Takashi Iwai, Jaroslav Kysela, Greg Kroah-Hartman, linux-sound,
linux-usb, linux-kernel
On Wed, Mar 18, 2026 at 08:19:39AM +0100, Takashi Iwai wrote:
> On Tue, 17 Mar 2026 18:35:16 +0100,
> Cássio Gabriel wrote:
> >
> > On Tue, Mar 17, 2026 at 10:03:10AM +0100, Takashi Iwai wrote:
> > > On Tue, 17 Mar 2026 05:22:04 +0100,
> > > Cássio Gabriel wrote:
> > > >
> > > > get_alias_quirk() resolves a quirk for an aliased USB ID by scanning
> > > > usb_audio_ids[], but it currently checks only the vendor/product pair.
> > > >
> > > > This is weak for quirk table entries that also depend on additional
> > > > USB_DEVICE_ID match fields, such as device or interface class,
> > > > subclass, protocol, interface number, or bcdDevice range.
> > > >
> > > > Rework the alias lookup so that it still uses the aliased vid:pid as
> > > > the initial lookup key, but validates the remaining match_flags
> > > > constraints of each candidate entry against the real device and
> > > > interface descriptors before returning the quirk.
> > > >
> > > > Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
> > > > ---
> > > > Changes in v2:
> > > > - drop the temporary usb_device_id reconstruction approach
> > > > - validate only the remaining match_flags explicitly
> > > > - pass struct usb_interface * to get_alias_quirk()
> > > > - Link to v1: https://lore.kernel.org/r/20260314-alsa-usb-fix-quirk-alias-v1-1-3269998f7ada@gmail.com
> > > > ---
> > > > sound/usb/card.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-------
> > > > 1 file changed, 64 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/sound/usb/card.c b/sound/usb/card.c
> > > > index fd81f32a66fb..153085a77d43 100644
> > > > --- a/sound/usb/card.c
> > > > +++ b/sound/usb/card.c
> > > > @@ -864,21 +864,77 @@ static void find_last_interface(struct snd_usb_audio *chip)
> > > > usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface);
> > > > }
> > > >
> > > > +/*
> > > > + * Match aliased vid:pid first, then validate remaining fields against
> > > > + * the real device and interface descriptors.
> > > > + */
> > > > +static bool snd_usb_match_alias_entry(struct usb_interface *intf,
> > > > + const struct usb_device_id *id,
> > > > + u32 alias_id)
> > > > +{
> > > > + struct usb_device *dev = interface_to_usbdev(intf);
> > > > + const struct usb_host_interface *alt = intf->cur_altsetting;
> > > > + const struct usb_interface_descriptor *intfd = &alt->desc;
> > > > + const struct usb_device_descriptor *devd = &dev->descriptor;
> > > > + u16 bcd = le16_to_cpu(devd->bcdDevice);
> > > > +
> > > > + /* Match aliased vendor/product */
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
> > > > + id->idVendor != USB_ID_VENDOR(alias_id))
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
> > > > + id->idProduct != USB_ID_PRODUCT(alias_id))
> > > > + return false;
> > > > + /* Match real device descriptor constraints */
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
> > > > + bcd < id->bcdDevice_lo)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
> > > > + bcd > id->bcdDevice_hi)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
> > > > + devd->bDeviceClass != id->bDeviceClass)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
> > > > + devd->bDeviceSubClass != id->bDeviceSubClass)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
> > > > + devd->bDeviceProtocol != id->bDeviceProtocol)
> > > > + return false;
> > > > + /* Match real interface descriptor constraints */
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
> > > > + intfd->bInterfaceClass != id->bInterfaceClass)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
> > > > + intfd->bInterfaceSubClass != id->bInterfaceSubClass)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
> > > > + intfd->bInterfaceProtocol != id->bInterfaceProtocol)
> > > > + return false;
> > > > + if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER) &&
> > > > + intfd->bInterfaceNumber != id->bInterfaceNumber)
> > > > + return false;
> > > > +
> > > > + return true;
> > > > +}
> > >
> > > Hrm, it became larger than I wished.
> > > You compared with another implementation and decided to choose this
> > > version?
> > >
> >
> > Hi,
> >
> > I went with the explicit matching path in v2 because I wanted to keep
> > the alias lookup based on the aliased vid:pid while validating the
> > remaining match_flags against the real descriptors.
> >
> > > An alternative would be to have a copy of usb_device_id like your
> > > previous version, and clear match_flags bits with
> > > ~USB_DEVICE_ID_MATCH_DEVICE. If match_flags becomes 0, it passes.
> > > Otherwise call usb_match_one_id().
> >
> > thanks, that makes sense.
> >
> > What do you think about this approach?
> > ```
> > static const struct snd_usb_audio_quirk *
> > get_alias_quirk(struct usb_interface *intf, unsigned int id)
> > {
> > const struct usb_device_id *p;
> > struct usb_device_id match_id;
> >
> > for (p = usb_audio_ids; p->match_flags; p++) {
> > if ((p->match_flags & USB_DEVICE_ID_MATCH_DEVICE) !=
> > USB_DEVICE_ID_MATCH_DEVICE)
> > continue;
> >
> > if (p->idVendor != USB_ID_VENDOR(id) ||
> > p->idProduct != USB_ID_PRODUCT(id))
> > continue;
> >
> > match_id = *p;
> > match_id.match_flags &= ~USB_DEVICE_ID_MATCH_DEVICE;
> > if (!match_id.match_flags || usb_match_one_id(intf, &match_id))
> > return (const struct snd_usb_audio_quirk *)
> > p->driver_info;
> > }
> >
> > return NULL;
> > }
> > ```
>
> Yes, that's what I had in mind.
>
>
> thanks,
>
> Takashi
Nice, I'm going to send you the v3 patch with the fixes.
Thanks,
Cássio.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2026-03-18 12:06 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-03-17 4:22 [PATCH v2] ALSA: usb-audio: validate full match when resolving quirk aliases Cássio Gabriel
2026-03-17 9:03 ` Takashi Iwai
2026-03-17 17:35 ` Cássio Gabriel
2026-03-18 7:19 ` Takashi Iwai
2026-03-18 12:06 ` Cássio Gabriel
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