[PATCH net 2/2] skbuff: skb_copy_ubufs must release uarg even without user frags

[Willem de Bruijn]

From: Willem de Bruijn <will...@google.com>

skb_copy_ubufs creates a private copy of frags[] to release its hold
on user frags, then calls uarg->callback to notify the owner.

Call uarg->callback even when no frags exist. This edge case can
happen when zerocopy_sg_from_iter finds enough room in skb_headlen
to copy all the data.

Fixes: 3ece782693c4 ("sock: skb_copy_ubufs support for compound pages")
Signed-off-by: Willem de Bruijn <will...@google.com>
---
 net/core/skbuff.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index edf40ac0cd07..a3cb0be4c6f3 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1178,7 +1178,7 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
        u32 d_off;
 
        if (!num_frags)
-               return 0;
+               goto release;
 
        if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
                return -EINVAL;
@@ -1238,6 +1238,7 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
        __skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
        skb_shinfo(skb)->nr_frags = new_frags;
 
+release:
        skb_zcopy_clear(skb, false);
        return 0;
 }
-- 
2.15.1.620.gb9897f4670-goog