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...