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 <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: alsa-devel@alsa-project.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230922175046.work.766-kees@kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/usx2y/usbusx2y.h b/sound/usb/usx2y/usbusx2y.h
index 8d82f5cc2fe1c8be461a4ca53079417fed7153c4..391fd7b4ed5ef6aaae298da9ed9d55688e677664 100644 (file)
--- 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 5197599e7aa61bb9df5a775b88ee05df4798f647..ca7888495a9f40f0a2249c11c76d6e7c093289a1 100644 (file)
--- 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;