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_...
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 --- 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;