diff mbox

[v4,1/5] skbuff: return -EMSGSIZE in skb_to_sgvec to prevent overflow

Message ID 20170425150419.2060-1-Jason@zx2c4.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jason A. Donenfeld April 25, 2017, 3:04 p.m. UTC 
This is a defense-in-depth measure in response to bugs like
4d6fa57b4dab ("macsec: avoid heap overflow in skb_to_sgvec")

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
v4 fixes the commit message and moves the check into the inner-most if.

 net/core/skbuff.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Comments

David Miller April 25, 2017, 3:17 p.m. UTC | #1 
John this isn't how it works.

When you submit new versions of a patch that are part of a patch
series, you must resubmit the entire series not just the patches which
are changing.

Thanks.
diff mbox

Patch

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f86bf69cfb8d..e75640006d78 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3489,7 +3489,9 @@  void __init skb_init(void)
  *	@len: Length of buffer space to be mapped
  *
  *	Fill the specified scatter-gather list with mappings/pointers into a
- *	region of the buffer space attached to a socket buffer.
+ *	region of the buffer space attached to a socket buffer. Returns either
+ *	the number of scatterlist items used, or -EMSGSIZE if the contents
+ *	could not fit.
  */
 static int
 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
@@ -3517,6 +3519,8 @@  __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
 		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
 		if ((copy = end - offset) > 0) {
 			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+			if (elt && sg_is_last(&sg[elt - 1]))
+				return -EMSGSIZE;
 
 			if (copy > len)
 				copy = len;
@@ -3537,6 +3541,9 @@  __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
 
 		end = start + frag_iter->len;
 		if ((copy = end - offset) > 0) {
+			if (elt && sg_is_last(&sg[elt - 1]))
+				return -EMSGSIZE;
+
 			if (copy > len)
 				copy = len;
 			elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
@@ -3581,6 +3588,9 @@  int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int le
 {
 	int nsg = __skb_to_sgvec(skb, sg, offset, len);
 
+	if (nsg <= 0)
+		return nsg;
+
 	sg_mark_end(&sg[nsg - 1]);
 
 	return nsg;