| Message ID | 20220927003903.1941873-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | wifi: nl80211: Split memcpy() of struct nl80211_wowlan_tcp_data_token flexible array | expand |
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@chromium.org/ > > Cc: Johannes Berg <johannes@sipsolutions.net> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Eric Dumazet <edumazet@google.com> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Paolo Abeni <pabeni@redhat.com> > Cc: linux-wireless@vger.kernel.org > Cc: netdev@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > 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............................................^^^ -- Gustavo > } > > trig->tcp = cfg; > -- > 2.34.1 >
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@chromium.org/ > > > > Cc: Johannes Berg <johannes@sipsolutions.net> > > Cc: "David S. Miller" <davem@davemloft.net> > > Cc: Eric Dumazet <edumazet@google.com> > > Cc: Jakub Kicinski <kuba@kernel.org> > > Cc: Paolo Abeni <pabeni@redhat.com> > > Cc: linux-wireless@vger.kernel.org > > Cc: netdev@vger.kernel.org > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > 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
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); } trig->tcp = cfg;
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@chromium.org/ Cc: Johannes Berg <johannes@sipsolutions.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: linux-wireless@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- net/wireless/nl80211.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)