[IPV6]: IPV6_CHECKSUM socket option can corrupt kernel memory
So here is a patch that introduces skb_store_bits -- the opposite of
skb_copy_bits, and uses them to read/write the csum field in rawv6.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 5488ad0..3e2ad0a 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -34,6 +34,7 @@
#include <linux/netfilter_ipv6.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
+#include <asm/bug.h>
#include <net/ip.h>
#include <net/sock.h>
@@ -452,12 +453,15 @@
}
static int rawv6_push_pending_frames(struct sock *sk, struct flowi *fl,
- struct raw6_sock *rp, int len)
+ struct raw6_sock *rp)
{
+ struct inet_sock *inet = inet_sk(sk);
struct sk_buff *skb;
int err = 0;
- u16 *csum;
+ int offset;
+ int len;
u32 tmp_csum;
+ u16 csum;
if (!rp->checksum)
goto send;
@@ -465,10 +469,10 @@
if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
goto out;
- if (rp->offset + 1 < len)
- csum = (u16 *)(skb->h.raw + rp->offset);
- else {
+ offset = rp->offset;
+ if (offset >= inet->cork.length - 1) {
err = -EINVAL;
+ ip6_flush_pending_frames(sk);
goto out;
}
@@ -479,23 +483,46 @@
*/
tmp_csum = skb->csum;
} else {
+ struct sk_buff *csum_skb = NULL;
tmp_csum = 0;
skb_queue_walk(&sk->sk_write_queue, skb) {
tmp_csum = csum_add(tmp_csum, skb->csum);
+
+ if (csum_skb)
+ continue;
+
+ len = skb->len - (skb->h.raw - skb->data);
+ if (offset >= len) {
+ offset -= len;
+ continue;
+ }
+
+ csum_skb = skb;
}
+
+ skb = csum_skb;
}
+ offset += skb->h.raw - skb->data;
+ if (skb_copy_bits(skb, offset, &csum, 2))
+ BUG();
+
/* in case cksum was not initialized */
- if (unlikely(*csum))
- tmp_csum = csum_sub(tmp_csum, *csum);
+ if (unlikely(csum))
+ tmp_csum = csum_sub(tmp_csum, csum);
- *csum = csum_ipv6_magic(&fl->fl6_src,
- &fl->fl6_dst,
- len, fl->proto, tmp_csum);
+ tmp_csum = csum_ipv6_magic(&fl->fl6_src,
+ &fl->fl6_dst,
+ inet->cork.length, fl->proto, tmp_csum);
- if (*csum == 0)
- *csum = -1;
+ if (tmp_csum == 0)
+ tmp_csum = -1;
+
+ csum = tmp_csum;
+ if (skb_store_bits(skb, offset, &csum, 2))
+ BUG();
+
send:
err = ip6_push_pending_frames(sk);
out:
@@ -774,7 +801,7 @@
if (err)
ip6_flush_pending_frames(sk);
else if (!(msg->msg_flags & MSG_MORE))
- err = rawv6_push_pending_frames(sk, &fl, rp, len);
+ err = rawv6_push_pending_frames(sk, &fl, rp);
}
done:
ip6_dst_store(sk, dst,