[NET]: Fix incorrect sg_mark_end() calls.
This fixes scatterlist corruptions added by
commit 68e3f5dd4db62619fdbe520d36c9ebf62e672256
[CRYPTO] users: Fix up scatterlist conversion errors
The issue is that the code calls sg_mark_end() which clobbers the
sg_page() pointer of the final scatterlist entry.
The first part fo the fix makes skb_to_sgvec() do __sg_mark_end().
After considering all skb_to_sgvec() call sites the most correct
solution is to call __sg_mark_end() in skb_to_sgvec() since that is
what all of the callers would end up doing anyways.
I suspect this might have fixed some problems in virtio_net which is
the sole non-crypto user of skb_to_sgvec().
Other similar sg_mark_end() cases were converted over to
__sg_mark_end() as well.
Arguably sg_mark_end() is a poorly named function because it doesn't
just "mark", it clears out the page pointer as a side effect, which is
what led to these bugs in the first place.
The one remaining plain sg_mark_end() call is in scsi_alloc_sgtable()
and arguably it could be converted to __sg_mark_end() if only so that
we can delete this confusing interface from linux/scatterlist.h
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 573e172..64b50ff 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2028,8 +2028,8 @@
* Fill the specified scatter-gather list with mappings/pointers into a
* region of the buffer space attached to a socket buffer.
*/
-int
-skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
+static int
+__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
@@ -2078,7 +2078,8 @@
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
- elt += skb_to_sgvec(list, sg+elt, offset - start, copy);
+ elt += __skb_to_sgvec(list, sg+elt, offset - start,
+ copy);
if ((len -= copy) == 0)
return elt;
offset += copy;
@@ -2090,6 +2091,15 @@
return elt;
}
+int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
+{
+ int nsg = __skb_to_sgvec(skb, sg, offset, len);
+
+ __sg_mark_end(&sg[nsg - 1]);
+
+ return nsg;
+}
+
/**
* skb_cow_data - Check that a socket buffer's data buffers are writable
* @skb: The socket buffer to check.