On Mon, Sep 26, 2022 at 08:33:47PM -0500, Gustavo A. R. Silva wrote: > On Mon, Sep 26, 2022 at 05:39:03PM -0700, Kees Cook wrote: > > To work around a misbehavior of the compiler's ability to see into > > composite flexible array structs (as detailed in the coming memcpy() > > hardening series[1]), split the memcpy() of the header and the payload > > so no false positive run-time overflow warning will be generated. > > > > [1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keescook@xxxxxxxxxxxx/ > > > > Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> > > Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> > > Cc: Eric Dumazet <edumazet@xxxxxxxxxx> > > Cc: Jakub Kicinski <kuba@xxxxxxxxxx> > > Cc: Paolo Abeni <pabeni@xxxxxxxxxx> > > Cc: linux-wireless@xxxxxxxxxxxxxxx > > Cc: netdev@xxxxxxxxxxxxxxx > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > net/wireless/nl80211.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c > > index 2705e3ee8fc4..461897933e92 100644 > > --- a/net/wireless/nl80211.c > > +++ b/net/wireless/nl80211.c > > @@ -13171,7 +13171,8 @@ static int nl80211_parse_wowlan_tcp(struct cfg80211_registered_device *rdev, > > wake_mask_size); > > if (tok) { > > cfg->tokens_size = tokens_size; > > - memcpy(&cfg->payload_tok, tok, sizeof(*tok) + tokens_size); > > + cfg->payload_tok = *tok; > > + memcpy(cfg->payload_tok.token_stream, tok->token_stream, + tokens_size); > > There is a spurious '+' here............................................^^^ HUnh. Well. I learned a new C-ism today. A leading "+" is just accepted. I build-tested this, and it was happy. I just double-checked, and sure enough, it is actually parsing that line. I will send a v2. Thanks for catching that! ... That's such a weird typo we don't even have a checkpatch rule for it. :P -- Kees Cook
