Re: [PATCH v2 04/16] skbuff: Phase out ksize() fallback for frag_size
From: Paolo Abeni <pabeni@redhat.com>
Date: 2022-09-25 07:17:56
Also in:
dri-devel, intel-wired-lan, linux-btrfs, linux-fsdevel, linux-hardening, linux-media, linux-mm, lkml, llvm
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...
quoted hunk ↗ jump to hunk
, 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 <redacted> --- 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