On Fri, Mar 20, 2026 at 11:42 AM Kees Cook <[email protected]> wrote: > > On Thu, Mar 19, 2026 at 06:02:12PM -0700, Rosen Penev wrote: > > There's no need to allocate these separately. > > > > Add __counted_by for extra runtime analysis. Moved counting variable > > allocation to right after allocation as required by __counted_by. > > > > Signed-off-by: Rosen Penev <[email protected]> > > This looks reasonable to me. > > One thought I've had while reviewing your flex-array patches is that I > want to make sure you're doing your test builds with > KCFLAGS=-Wflexible-array-member-not-at-end > so that you can validate there's no new uses of the target structures > being composed within other structures while making these changes. I did that globally. Too many pre-existing issues with that.
I mostly just run make menuconfig on linux-next and see what happens. > > That looks clear here, but I think going forward, it would be worth > mentioning it as part of the commit log. Something like: > > This structure is not composed within other structures, confirmed with > builds using -Wflexible-array-member-not-at-end. > > or similar. > > Reviewed-by: Kees Cook <[email protected]> > > -Kees > > > --- > > drivers/media/usb/em28xx/em28xx-cards.c | 18 ++---------------- > > drivers/media/usb/em28xx/em28xx.h | 3 ++- > > 2 files changed, 4 insertions(+), 17 deletions(-) > > > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c > > b/drivers/media/usb/em28xx/em28xx-cards.c > > index d7075ebabceb..c278e48b3428 100644 > > --- a/drivers/media/usb/em28xx/em28xx-cards.c > > +++ b/drivers/media/usb/em28xx/em28xx-cards.c > > @@ -3567,9 +3567,6 @@ void em28xx_free_device(struct kref *ref) > > if (!dev->disconnected) > > em28xx_release_resources(dev); > > > > - if (dev->ts == PRIMARY_TS) > > - kfree(dev->alt_max_pkt_size_isoc); > > - > > kfree(dev); > > } > > EXPORT_SYMBOL_GPL(em28xx_free_device); > > @@ -3912,21 +3909,13 @@ static int em28xx_usb_probe(struct usb_interface > > *intf, > > } > > > > /* allocate memory for our device state and initialize it */ > > - dev = kzalloc_obj(*dev); > > + dev = kzalloc_flex(*dev, alt_max_pkt_size_isoc, intf->num_altsetting); > > if (!dev) { > > retval = -ENOMEM; > > goto err; > > } > > > > - /* compute alternate max packet sizes */ > > - dev->alt_max_pkt_size_isoc = kcalloc(intf->num_altsetting, > > - > > sizeof(dev->alt_max_pkt_size_isoc[0]), > > - GFP_KERNEL); > > - if (!dev->alt_max_pkt_size_isoc) { > > - kfree(dev); > > - retval = -ENOMEM; > > - goto err; > > - } > > + dev->num_alt = intf->num_altsetting; > > > > /* Get endpoints */ > > for (i = 0; i < intf->num_altsetting; i++) { > > @@ -4028,8 +4017,6 @@ static int em28xx_usb_probe(struct usb_interface > > *intf, > > dev->dvb_ep_bulk ? " bulk" : "", > > dev->dvb_ep_isoc ? " isoc" : ""); > > > > - dev->num_alt = intf->num_altsetting; > > - > > if ((unsigned int)card[nr] < em28xx_bcount) > > dev->model = card[nr]; > > > > @@ -4163,7 +4150,6 @@ static int em28xx_usb_probe(struct usb_interface > > *intf, > > return 0; > > > > err_free: > > - kfree(dev->alt_max_pkt_size_isoc); > > kfree(dev); > > > > err: > > diff --git a/drivers/media/usb/em28xx/em28xx.h > > b/drivers/media/usb/em28xx/em28xx.h > > index f3449c240d21..1c2f92927889 100644 > > --- a/drivers/media/usb/em28xx/em28xx.h > > +++ b/drivers/media/usb/em28xx/em28xx.h > > @@ -730,7 +730,6 @@ struct em28xx { > > int packet_multiplier; // multiplier for wMaxPacketSize, used for > > // URB buffer size definition > > int num_alt; // number of alternative settings > > - unsigned int *alt_max_pkt_size_isoc; // array of isoc wMaxPacketSize > > unsigned int analog_xfer_bulk:1; // use bulk instead of isoc > > // transfers for analog > > int dvb_alt_isoc; // alternate setting for DVB isoc transfers > > @@ -772,6 +771,8 @@ struct em28xx { > > > > struct em28xx *dev_next; > > int ts; > > + > > + unsigned int alt_max_pkt_size_isoc[] __counted_by(num_alt); // array > > of isoc wMaxPacketSize > > }; > > > > #define kref_to_dev(d) container_of(d, struct em28xx, ref) > > -- > > 2.53.0 > > > > > > -- > Kees Cook
