6lowpan: move skb_free from error paths in decompression
Currently we ensure that the skb is freed on every error path in IPHC
decompression which makes it easy to introduce skb leaks. By centralising
the skb_free into the receive function it makes future decompression routines
easier to maintain. It does come at the expense of ensuring that the skb
passed into the decompression routine must not be copied.
Signed-off-by: Martin Townsend <mtownsend1973@gmail.com>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Acked-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
index cd5f8b8..aced97d 100644
--- a/net/6lowpan/iphc.c
+++ b/net/6lowpan/iphc.c
@@ -319,7 +319,7 @@
if (iphc1 & LOWPAN_IPHC_CID) {
pr_debug("CID flag is set, increase header with one\n");
if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context)))
- goto drop;
+ return -EINVAL;
}
hdr.version = 6;
@@ -331,7 +331,7 @@
*/
case 0: /* 00b */
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
- goto drop;
+ return -EINVAL;
memcpy(&hdr.flow_lbl, &skb->data[0], 3);
skb_pull(skb, 3);
@@ -344,7 +344,7 @@
*/
case 2: /* 10b */
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
- goto drop;
+ return -EINVAL;
hdr.priority = ((tmp >> 2) & 0x0f);
hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
@@ -354,7 +354,7 @@
*/
case 1: /* 01b */
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
- goto drop;
+ return -EINVAL;
hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
@@ -371,7 +371,7 @@
if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
/* Next header is carried inline */
if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
- goto drop;
+ return -EINVAL;
pr_debug("NH flag is set, next header carried inline: %02x\n",
hdr.nexthdr);
@@ -383,7 +383,7 @@
} else {
if (lowpan_fetch_skb(skb, &hdr.hop_limit,
sizeof(hdr.hop_limit)))
- goto drop;
+ return -EINVAL;
}
/* Extract SAM to the tmp variable */
@@ -402,7 +402,7 @@
/* Check on error of previous branch */
if (err)
- goto drop;
+ return -EINVAL;
/* Extract DAM to the tmp variable */
tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
@@ -417,7 +417,7 @@
tmp);
if (err)
- goto drop;
+ return -EINVAL;
}
} else {
err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
@@ -425,7 +425,7 @@
pr_debug("dest: stateless compression mode %d dest %pI6c\n",
tmp, &hdr.daddr);
if (err)
- goto drop;
+ return -EINVAL;
}
/* UDP data uncompression */
@@ -434,16 +434,14 @@
const int needed = sizeof(struct udphdr) + sizeof(hdr);
if (uncompress_udp_header(skb, &uh))
- goto drop;
+ return -EINVAL;
/* replace the compressed UDP head by the uncompressed UDP
* header
*/
err = skb_cow(skb, needed);
- if (unlikely(err)) {
- kfree_skb(skb);
+ if (unlikely(err))
return err;
- }
skb_push(skb, sizeof(struct udphdr));
skb_reset_transport_header(skb);
@@ -455,10 +453,8 @@
hdr.nexthdr = UIP_PROTO_UDP;
} else {
err = skb_cow(skb, sizeof(hdr));
- if (unlikely(err)) {
- kfree_skb(skb);
+ if (unlikely(err))
return err;
- }
}
hdr.payload_len = htons(skb->len);
@@ -478,9 +474,6 @@
raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
return 0;
-drop:
- kfree_skb(skb);
- return -EINVAL;
}
EXPORT_SYMBOL_GPL(lowpan_header_decompress);