CVE-2017-13011 (published 2017-09-14T06:29Z)

Several protocol parsers in tcpdump before 4.9.2 could cause a buffer overflow in util-print.c:bittok2str_internal().

Severity: HIGH
CVSS v2 base score: 7.5 (AV:N/AC:L/Au:N/C:P/I:P/A:P)
CVSS v3 base score: 9.8, CRITICAL (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/the-tcpdump-group/tcpdump
commit_details: repo_url: https://github.com/the-tcpdump-group/tcpdump
author: Guy Harris
author_date: 2017-03-15 12:12:21-07:00
msg: CVE-2017-13011/Properly check for buffer overflow in bittok2str_internal().

Also, make the buffer bigger.

This fixes a buffer overflow discovered by Bhargava Shastry,
SecT/TU Berlin.

Add a test using the capture file supplied by the reporter(s), modified
so the capture file won't be rejected as an invalid capture.
repository: repo_url: https://github.com/the-tcpdump-group/tcpdump
repo_name: the-tcpdump-group/tcpdump
description: the TCPdump network dissector
repo_language: C
owner: the-tcpdump-group
file_changes: filename: TESTLIST
change_type: ModificationType.MODIFY
diff: @@ -507,6 +507,9 @@ juniper_es		juniper_es.pcap			juniper_es.out	-vvv -e
 l2tp-avp-overflow	l2tp-avp-overflow.pcap		l2tp-avp-overflow.out	-v
 pktap-heap-overflow	pktap-heap-overflow.pcap	pktap-heap-overflow.out	-v
 
+# bad packets from Bhargava Shastry
+lldp_asan		lldp_asan.pcap			lldp_asan.out	-v
+
 # RTP tests
 # fuzzed pcap
 rtp-seg-fault-1  rtp-seg-fault-1.pcap  rtp-seg-fault-1.out  -v -T rtp

programming_language: Shell
filename: lldp_asan.out
change_type: ModificationType.ADD
diff: @@ -0,0 +1,14 @@
+LLDP, length 296
+	Chassis ID TLV (1), length 6
+	  Subtype Network address (5): AFI IPv4 (1): 0.0.32.0
+	Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
+	  MAC/PHY configuration/status Subtype (1)
+	    autonegotiation [none] (0x00)
+	    PMD autoneg capability [10BASE-T hdx, 10BASE-T fdx, 100BASE-T4, 100BASE-TX hdx, 100BASE-TX fdx, 100BASE-T2 hdx, 100BASE-T2 fdx, Pause for fdx links, Asym PAUSE for fdx, Sym PAUSE for fdx, Asym and Sym PAUSE for fdx, 1000BASE-{X LX SX CX} hdx, 1000BASE-{X LX SX CX} fdx, 1000BASE-T hdx, 1000BASE-T fdx] (0xffff)
+	    MAU type unknown (0x2000)
+	Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
+	  MAC/PHY configuration/status Subtype (1)
+	    autonegotiation [none] (0x00)
+	    PMD autoneg capability [Pause for fdx links, Asym PAUSE for fdx, Sym PAUSE for fdx, Asym and Sym PAUSE for fdx, 1000BASE-{X LX SX CX} hdx, 1000BASE-{X LX SX CX} fdx, 1000BASE-T hdx] (0x00fe)
+	    MAU type unknown (0x0f00)
+	End TLV (0), length 0

programming_language: Batchfile
filename: util-print.c
change_type: ModificationType.MODIFY
diff: @@ -523,8 +523,9 @@ static char *
 bittok2str_internal(register const struct tok *lp, register const char *fmt,
 	   register u_int v, const char *sep)
 {
-        static char buf[256]; /* our stringbuffer */
-        int buflen=0;
+        static char buf[1024+1]; /* our string buffer */
+        char *bufp = buf;
+        size_t space_left = sizeof(buf), string_size;
         register u_int rotbit; /* this is the bit we rotate through all bitpositions */
         register u_int tokval;
         const char * sepstr = "";
@@ -539,8 +540,20 @@ bittok2str_internal(register const struct tok *lp, register const char *fmt,
                  */
 		if (tokval == (v&rotbit)) {
                     /* ok we have found something */
-                    buflen+=snprintf(buf+buflen, sizeof(buf)-buflen, "%s%s",
-                                     sepstr, lp->s);
+                    if (space_left <= 1)
+                        return (buf); /* only enough room left for NUL, if that */
+                    string_size = strlcpy(bufp, sepstr, space_left);
+                    if (string_size >= space_left)
+                        return (buf);    /* we ran out of room */
+                    bufp += string_size;
+                    space_left -= string_size;
+                    if (space_left <= 1)
+                        return (buf); /* only enough room left for NUL, if that */
+                    string_size = strlcpy(bufp, lp->s, space_left);
+                    if (string_size >= space_left)
+                        return (buf);    /* we ran out of room */
+                    bufp += string_size;
+                    space_left -= string_size;
                     sepstr = sep;
                     break;
                 }
@@ -549,7 +562,7 @@ bittok2str_internal(register const struct tok *lp, register const char *fmt,
             lp++;
 	}
 
-        if (buflen == 0)
+        if (bufp == buf)
             /* bummer - lets print the "unknown" message as advised in the fmt string if we got one */
             (void)snprintf(buf, sizeof(buf), fmt == NULL ? "#%08x" : fmt, v);
         return (buf);

programming_language: C