[lwip-devel] [bug #58554] Memory disclosure in the 6LoWPAN implementation

[Wenqiang Li]

URL:
  <https://savannah.nongnu.org/bugs/?58554>

                 Summary: Memory disclosure in the 6LoWPAN implementation
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: silentdawn
            Submitted on: Fri 12 Jun 2020 05:24:21 PM UTC
                Category: Security-related
                Severity: 3 - Normal
              Item Group: Crash Error
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: git head

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Details:

Type:
Buffer overflow

Description:
This bug is similar to bug #58553. The function zepif_linkoutput() tries to
parse an 6LoWPAN TX packet as UDP broadcast. When it calls the function
pbuf_take_at() as shown in line 204 of zepif.c, the same incorrectly used
parameters are passed as the Bug 2. In particular, the p->tot_len is the total
length of the p->payload and all payloads length of its following pbuf. If
p->tot_len is larger than the length of p->payload, the memory will leak to
remote attackers through the network. To send the whole packet, it should use
a loop to traverse the list of p->next and send all the payloads with length
p->tot_len.
        
168
zepif_linkoutput(struct netif *netif, struct pbuf *p){

...
204
err = pbuf_take_at(q, p->payload, p->tot_len, sizeof(struct zep_hdr));

...
214
}

Result:
Memory disclosure. 





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