On Wed, Jul 28, 2021 at 11:23:23AM +0200, David Sterba wrote: > On Wed, Jul 28, 2021 at 10:35:56AM +0300, Dan Carpenter wrote: > > @@ -372,7 +372,7 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local, > > ieee80211_calculate_rx_timestamp(local, status, > > mpdulen, 0), > > pos); > > - rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT); > > + rthdr->data.it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT); > > A drive-by comment, not related to the patchset, but rather the > ieee80211 driver itself. > > Shift expressions with (1 << NUMBER) can be subtly broken once the > NUMBER is 31 and the value gets silently cast to a 64bit type. It will > become 0xfffffffff80000000. > > I've checked the IEEE80211_RADIOTAP_* defintions if this is even remotely > possible and yes, IEEE80211_RADIOTAP_EXT == 31. Fortunatelly it seems to > be used with used with a 32bit types (eg. _bitmap_shifter) so there are > no surprises. > > The recommended practice is to always use unsigned types for shifts, so > "1U << ..." at least. Ah, good catch! I think just using BIT() is the right replacement here, yes? I suppose that should be a separate patch. -- Kees Cook
