Merge branch 'skb-sgvec-overflow'

Jason A. Donenfeld says:

====================
net: Avoiding stack overflow in skb_to_sgvec

The recent bug with macsec and historical one with virtio have
indicated that letting skb_to_sgvec trounce all over an sglist
without checking the length is probably a bad idea. And it's not
necessary either: an sglist already explicitly marks its last
item, and the initialization functions are diligent in doing so.
Thus there's a clear way of avoiding future overflows.

So, this patchset, from a high level, makes skb_to_sgvec return
a potential error code, and then adjusts all callers to check
for the error code. There are two situations in which skb_to_sgvec
might return such an error:

   1) When the passed in sglist is too small; and
   2) When the passed in skbuff is too deeply nested.

So, the first patch in this series handles the issues with
skb_to_sgvec directly, and the remaining ones then handle the call
sites.
====================

Signed-off-by: David S. Miller <[email protected]>

1 files changed, 4 insertions, 4 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 45a59c1e0cc7..d460a4cbda1c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -953,10 +953,10 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
 				     unsigned int headroom);
 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
 				int newtailroom, gfp_t priority);
-int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
-			int offset, int len);
-int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
-		 int len);
+int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
+				     int offset, int len);
+int __must_check skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg,
+			      int offset, int len);
 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
 int skb_pad(struct sk_buff *skb, int pad);
 #define dev_kfree_skb(a)	consume_skb(a)