Merge 5.14-rc3 into char-misc-next

We need the char-misc fixes from 5.14-rc3 into here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 16 insertions, 2 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f63de967ac25..fc7942c0dddc 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -663,7 +663,7 @@ static void skb_release_data(struct sk_buff *skb)
 	if (skb->cloned &&
 	    atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
 			      &shinfo->dataref))
-		return;
+		goto exit;
 
 	skb_zcopy_clear(skb, true);
 
@@ -674,6 +674,17 @@ static void skb_release_data(struct sk_buff *skb)
 		kfree_skb_list(shinfo->frag_list);
 
 	skb_free_head(skb);
+exit:
+	/* When we clone an SKB we copy the reycling bit. The pp_recycle
+	 * bit is only set on the head though, so in order to avoid races
+	 * while trying to recycle fragments on __skb_frag_unref() we need
+	 * to make one SKB responsible for triggering the recycle path.
+	 * So disable the recycling bit if an SKB is cloned and we have
+	 * additional references to to the fragmented part of the SKB.
+	 * Eventually the last SKB will have the recycling bit set and it's
+	 * dataref set to 0, which will trigger the recycling
+	 */
+	skb->pp_recycle = 0;
 }
 
 /*
@@ -3011,8 +3022,11 @@ skb_zerocopy_headlen(const struct sk_buff *from)
 
 	if (!from->head_frag ||
 	    skb_headlen(from) < L1_CACHE_BYTES ||
-	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
+	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
 		hlen = skb_headlen(from);
+		if (!hlen)
+			hlen = from->len;
+	}
 
 	if (skb_has_frag_list(from))
 		hlen = from->len;