2023-09-22 22:25:32

by Kees Cook

Subject: [PATCH] ALSA: usx2y: Annotate struct snd_usx2y_urb_seq with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct snd_usx2y_urb_seq.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
sound/usb/usx2y/usbusx2y.h | 2 +-
sound/usb/usx2y/usbusx2yaudio.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/usb/usx2y/usbusx2y.h b/sound/usb/usx2y/usbusx2y.h
index 8d82f5cc2fe1..391fd7b4ed5e 100644
--- a/sound/usb/usx2y/usbusx2y.h
+++ b/sound/usb/usx2y/usbusx2y.h
@@ -18,7 +18,7 @@ struct snd_usx2y_async_seq {
struct snd_usx2y_urb_seq {
int submitted;
int len;
- struct urb *urb[];
+ struct urb *urb[] __counted_by(len);
};

#include "usx2yhwdeppcm.h"
diff --git a/sound/usb/usx2y/usbusx2yaudio.c b/sound/usb/usx2y/usbusx2yaudio.c
index 5197599e7aa6..ca7888495a9f 100644
--- a/sound/usb/usx2y/usbusx2yaudio.c
+++ b/sound/usb/usx2y/usbusx2yaudio.c
@@ -681,6 +681,7 @@ static int usx2y_rate_set(struct usx2ydev *usx2y, int rate)
err = -ENOMEM;
goto cleanup;
}
+ us->len = NOOF_SETRATE_URBS;
usbdata = kmalloc_array(NOOF_SETRATE_URBS, sizeof(int),
GFP_KERNEL);
if (!usbdata) {
@@ -702,7 +703,6 @@ static int usx2y_rate_set(struct usx2ydev *usx2y, int rate)
if (err < 0)
goto cleanup;
us->submitted = 0;
- us->len = NOOF_SETRATE_URBS;
usx2y->us04 = us;
wait_event_timeout(usx2y->in04_wait_queue, !us->len, HZ);
usx2y->us04 = NULL;
--
2.34.1

2023-09-23 17:43:34

by Gustavo A. R. Silva

Subject: Re: [PATCH] ALSA: usx2y: Annotate struct snd_usx2y_urb_seq with __counted_by

On 9/22/23 11:50, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct snd_usx2y_urb_seq.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Jaroslav Kysela <[email protected]>
> Cc: Takashi Iwai <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

Thanks
--
Gustavo

> ---
> sound/usb/usx2y/usbusx2y.h | 2 +-
> sound/usb/usx2y/usbusx2yaudio.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/sound/usb/usx2y/usbusx2y.h b/sound/usb/usx2y/usbusx2y.h
> index 8d82f5cc2fe1..391fd7b4ed5e 100644
> --- a/sound/usb/usx2y/usbusx2y.h
> +++ b/sound/usb/usx2y/usbusx2y.h
> @@ -18,7 +18,7 @@ struct snd_usx2y_async_seq {
> struct snd_usx2y_urb_seq {
> int submitted;
> int len;
> - struct urb *urb[];
> + struct urb *urb[] __counted_by(len);
> };
>
> #include "usx2yhwdeppcm.h"
> diff --git a/sound/usb/usx2y/usbusx2yaudio.c b/sound/usb/usx2y/usbusx2yaudio.c
> index 5197599e7aa6..ca7888495a9f 100644
> --- a/sound/usb/usx2y/usbusx2yaudio.c
> +++ b/sound/usb/usx2y/usbusx2yaudio.c
> @@ -681,6 +681,7 @@ static int usx2y_rate_set(struct usx2ydev *usx2y, int rate)
> err = -ENOMEM;
> goto cleanup;
> }
> + us->len = NOOF_SETRATE_URBS;
> usbdata = kmalloc_array(NOOF_SETRATE_URBS, sizeof(int),
> GFP_KERNEL);
> if (!usbdata) {
> @@ -702,7 +703,6 @@ static int usx2y_rate_set(struct usx2ydev *usx2y, int rate)
> if (err < 0)
> goto cleanup;
> us->submitted = 0;
> - us->len = NOOF_SETRATE_URBS;
> usx2y->us04 = us;
> wait_event_timeout(usx2y->in04_wait_queue, !us->len, HZ);
> usx2y->us04 = NULL;

2023-09-23 17:52:02

by Takashi Iwai

Subject: Re: [PATCH] ALSA: usx2y: Annotate struct snd_usx2y_urb_seq with __counted_by

On Fri, 22 Sep 2023 19:50:47 +0200,
Kees Cook wrote:
>
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct snd_usx2y_urb_seq.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Jaroslav Kysela <[email protected]>
> Cc: Takashi Iwai <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Applied now. Thanks.


Takashi