[PATCH 4.14 115/146] skbuff: skb_copy_ubufs must release uarg even without user frags

Greg Kroah-Hartman
2018-01-01T14:48:10Z

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

[ Upstream commit b90ddd568792bcb0054eaf0f61785c8f80c3bd1c ]

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 <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/skbuff.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1182,7 +1182,7 @@ int skb_copy_ubufs(struct sk_buff *skb,
u32 d_off;

if (!num_frags)
- return 0;
+ goto release;

if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
return -EINVAL;
@@ -1242,6 +1242,7 @@ int skb_copy_ubufs(struct sk_buff *skb,
__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;
}