6lowpan: read data from skb safely
Check if skb buffer can pull requested amount of bytes and return
an error in opposite case.
Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 32eb417..5c7bcf9 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -291,25 +291,26 @@
*hc06_ptr += 2;
}
-static u8 lowpan_fetch_skb_u8(struct sk_buff *skb)
+static inline int lowpan_fetch_skb_u8(struct sk_buff *skb, u8 *val)
{
- u8 ret;
+ if (unlikely(!pskb_may_pull(skb, 1)))
+ return -EINVAL;
- ret = skb->data[0];
+ *val = skb->data[0];
skb_pull(skb, 1);
- return ret;
+ return 0;
}
-static u16 lowpan_fetch_skb_u16(struct sk_buff *skb)
+static inline int lowpan_fetch_skb_u16(struct sk_buff *skb, u16 *val)
{
- u16 ret;
+ if (unlikely(!pskb_may_pull(skb, 2)))
+ return -EINVAL;
- BUG_ON(!pskb_may_pull(skb, 2));
-
- ret = skb->data[0] | (skb->data[1] << 8);
+ *val = skb->data[0] | (skb->data[1] << 8);
skb_pull(skb, 2);
- return ret;
+
+ return 0;
}
static int
@@ -318,7 +319,8 @@
struct udphdr *uh = udp_hdr(skb);
u8 tmp;
- tmp = lowpan_fetch_skb_u8(skb);
+ if (lowpan_fetch_skb_u8(skb, &tmp))
+ goto err;
if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
pr_debug("(%s): UDP header uncompression\n", __func__);
@@ -710,7 +712,9 @@
/* at least two bytes will be used for the encoding */
if (skb->len < 2)
goto drop;
- iphc0 = lowpan_fetch_skb_u8(skb);
+
+ if (lowpan_fetch_skb_u8(skb, &iphc0))
+ goto drop;
/* fragments assembling */
switch (iphc0 & LOWPAN_DISPATCH_MASK) {
@@ -722,8 +726,9 @@
u16 tag;
bool found = false;
- len = lowpan_fetch_skb_u8(skb); /* frame length */
- tag = lowpan_fetch_skb_u16(skb);
+ if (lowpan_fetch_skb_u8(skb, &len) || /* frame length */
+ lowpan_fetch_skb_u16(skb, &tag)) /* fragment tag */
+ goto drop;
/*
* check if frame assembling with the same tag is
@@ -747,7 +752,8 @@
if ((iphc0 & LOWPAN_DISPATCH_MASK) == LOWPAN_DISPATCH_FRAG1)
goto unlock_and_drop;
- offset = lowpan_fetch_skb_u8(skb); /* fetch offset */
+ if (lowpan_fetch_skb_u8(skb, &offset)) /* fetch offset */
+ goto unlock_and_drop;
/* if payload fits buffer, copy it */
if (likely((offset * 8 + skb->len) <= frame->length))
@@ -769,7 +775,10 @@
dev_kfree_skb(skb);
skb = frame->skb;
kfree(frame);
- iphc0 = lowpan_fetch_skb_u8(skb);
+
+ if (lowpan_fetch_skb_u8(skb, &iphc0))
+ goto unlock_and_drop;
+
break;
}
spin_unlock(&flist_lock);
@@ -780,7 +789,8 @@
break;
}
- iphc1 = lowpan_fetch_skb_u8(skb);
+ if (lowpan_fetch_skb_u8(skb, &iphc1))
+ goto drop;
_saddr = mac_cb(skb)->sa.hwaddr;
_daddr = mac_cb(skb)->da.hwaddr;
@@ -791,9 +801,8 @@
if (iphc1 & LOWPAN_IPHC_CID) {
pr_debug("(%s): CID flag is set, increase header with one\n",
__func__);
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &num_context))
goto drop;
- num_context = lowpan_fetch_skb_u8(skb);
}
hdr.version = 6;
@@ -805,9 +814,9 @@
* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
*/
case 0: /* 00b */
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &tmp))
goto drop;
- tmp = lowpan_fetch_skb_u8(skb);
+
memcpy(&hdr.flow_lbl, &skb->data[0], 3);
skb_pull(skb, 3);
hdr.priority = ((tmp >> 2) & 0x0f);
@@ -819,9 +828,9 @@
* ECN + DSCP (1 byte), Flow Label is elided
*/
case 1: /* 10b */
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &tmp))
goto drop;
- tmp = lowpan_fetch_skb_u8(skb);
+
hdr.priority = ((tmp >> 2) & 0x0f);
hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
hdr.flow_lbl[1] = 0;
@@ -832,9 +841,9 @@
* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
*/
case 2: /* 01b */
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &tmp))
goto drop;
- tmp = lowpan_fetch_skb_u8(skb);
+
hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
skb_pull(skb, 2);
@@ -853,9 +862,9 @@
/* Next Header */
if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
/* Next header is carried inline */
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &(hdr.nexthdr)))
goto drop;
- hdr.nexthdr = lowpan_fetch_skb_u8(skb);
+
pr_debug("(%s): NH flag is set, next header is carried "
"inline: %02x\n", __func__, hdr.nexthdr);
}
@@ -864,9 +873,8 @@
if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I)
hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
else {
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &(hdr.hop_limit)))
goto drop;
- hdr.hop_limit = lowpan_fetch_skb_u8(skb);
}
/* Extract SAM to the tmp variable */
@@ -894,10 +902,8 @@
pr_debug("(%s): destination address non-context-based"
" multicast compression\n", __func__);
if (0 < tmp && tmp < 3) {
- if (!skb->len)
+ if (lowpan_fetch_skb_u8(skb, &prefix[1]))
goto drop;
- else
- prefix[1] = lowpan_fetch_skb_u8(skb);
}
err = lowpan_uncompress_addr(skb, &hdr.daddr, prefix,
