Message ID | 20220923202822.2667581-1-keescook@chromium.org (mailing list archive) |
---|---|
Headers | show |
Series | slab: Introduce kmalloc_size_roundup() | expand |
On Fri, 2022-09-23 at 13:28 -0700, Kees Cook wrote: > All callers of APIs that allowed a 0-sized frag_size appear to be > passing actual size information already AFAICS, not yet: drivers/net/ethernet/qlogic/qed/qed_ll2.c: skb = build_skb(buffer->data, 0); // -> __build_skb(..., 0) // -> __build_skb_around() drivers/net/ethernet/broadcom/bnx2.c: skb = build_skb(data, 0); I guess some more drivers have calls leading to __build_skb_around(..., 0) there are several call path to checks... > , so this use of ksize() can > be removed. However, just in case there is something still depending > on this behavior, issue a WARN and fall back to as before to ksize() > which means we'll also potentially get KASAN warnings. > > 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: netdev@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > net/core/skbuff.c | 18 ++++++++++-------- > 1 file changed, 10 insertions(+), 8 deletions(-) > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 0b30fbdbd0d0..84ca89c781cd 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -195,7 +195,11 @@ static void __build_skb_around(struct sk_buff *skb, void *data, > unsigned int frag_size) > { > struct skb_shared_info *shinfo; > - unsigned int size = frag_size ? : ksize(data); > + unsigned int size = frag_size; > + > + /* All callers should be setting frag size now? */ > + if (WARN_ON_ONCE(size == 0)) > + size = ksize(data); At some point in the future, I guess we could even drop this check, right? Thanks! Paolo
On Sun, Sep 25, 2022 at 09:17:40AM +0200, Paolo Abeni wrote: > On Fri, 2022-09-23 at 13:28 -0700, Kees Cook wrote: > > All callers of APIs that allowed a 0-sized frag_size appear to be > > passing actual size information already > > AFAICS, not yet: > > drivers/net/ethernet/qlogic/qed/qed_ll2.c: > skb = build_skb(buffer->data, 0); // -> __build_skb(..., 0) > // -> __build_skb_around() > > drivers/net/ethernet/broadcom/bnx2.c: > skb = build_skb(data, 0); > > I guess some more drivers have calls leading to > > __build_skb_around(..., 0) > > there are several call path to checks... Ah-ha! Thank you. I will try to hunt these down -- I think we can't remove the "secret resizing" effect of ksize() without fixing these. > > [...] > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > > index 0b30fbdbd0d0..84ca89c781cd 100644 > > --- a/net/core/skbuff.c > > +++ b/net/core/skbuff.c > > @@ -195,7 +195,11 @@ static void __build_skb_around(struct sk_buff *skb, void *data, > > unsigned int frag_size) > > { > > struct skb_shared_info *shinfo; > > - unsigned int size = frag_size ? : ksize(data); > > + unsigned int size = frag_size; > > + > > + /* All callers should be setting frag size now? */ > > + if (WARN_ON_ONCE(size == 0)) > > + size = ksize(data); > > At some point in the future, I guess we could even drop this check, > right? Alternatively, we might be able to ask the slab if "data" came from kmalloc or a kmem_cache, and if the former, do: data = krealloc(kmalloc_size_roundup(ksize(data), ...) But that seems ugly...