Fix two typos in v2.93 CHANGELOG

get_rdata() contains another instance of a crash caused by
a false value of RDLEN in a resource-record.

An RR containing name which is longer than the rdlen of the RR can
get get_rdata into a state where it calculates the length of the data
following the name as a negative number which is then promoted
to a very large positive number, and causing SIGSEGV.

This can be triggered by crafted packets from malicous DNS servers,
but only when DNSSEC validation is enabled. The attack packets do not
have to be correctly DNSSEC signed.

Thanks to Tristan G. for spotting this problem.

Also fix error handling for RRs with a fixed size fields in the specification
where the rrsize indicates that there are zero bytes in that position.

CHANGELOG

@@ -1,6 +1,6 @@
 version 2.93
 	Fix a corner-case in DNSSEC validation with wildcards. If we have
-	a wildcard record *.example.com and recieve a query for
+	a wildcard record *.example.com and receive a query for
 	a.example.com then that's OK, but we have to check that there isn't
 	an actual a.example.com record. The corner case is when we get a
 	query for *.example.com in that case the non-existence check
@@ -19,7 +19,7 @@ version 2.93
 	(eg rivcoed.org) will still fail. Thanks to Petr Menšík
 	for the bug report.
 
-	Fix DNSSEC fail with CNAME replies to DS queries. As CNAME reply
+	Fix DNSSEC fail with CNAME replies to DS queries. A CNAME reply
 	to a DNSSEC query was confusing the validation logic. It now
 	accepts a signed CNAME reply to a DS query as proof that no DS
 	exists at the domain. This fixes the DS/zone break detection logic.

man/dnsmasq.8

@@ -154,6 +154,9 @@ allows the log file to be rotated without stopping dnsmasq.
 .B --log-debug
 Enable extra logging intended for debugging rather than information.
 .TP
+.B --log-malloc
+Enable logging of memory allocation and release, for debugging.
+.TP
 .B --log-async[=<lines>]
 Enable asynchronous logging and optionally set the limit on the
 number of lines

src/dnssec.c

@@ -177,7 +177,7 @@ static int get_rdata(struct dns_header *header, size_t plen, struct rdata_state
 	  if ((state->c = state->end - state->ip) != 0)
 	    {
 	      state->op = state->ip;
-	      state->ip = state->end;;
+	      state->ip = state->end;
 	    }
 	  else
 	    return 0;
@@ -189,24 +189,28 @@ static int get_rdata(struct dns_header *header, size_t plen, struct rdata_state
 	  if (d == (u16)0)
 	    {
 	      /* domain-name, canonicalise */
-	      int len;
 	      
+	      /* If the name is malformed, or runs beyond the end of the RR, abort.
+		 under no circumstances should state->ip be beyond state->end since
+		 that will cause the run-out code above to turn the negative
+		 calculted length into a very large postive value for state->c
+		 and overrun the buffer. */
 	      if (!extract_name(header, plen, &state->ip, state->buff, EXTR_NAME_EXTRACT, 0) ||
-		  (len = to_wire(state->buff)) == 0)
-		continue;
-	      
-	      state->c = len;
+		  state->ip > state->end)
+		return 0;
+
+	      /* to_wire() always returns length > 0 */
+	      state->c = to_wire(state->buff);
 	      state->op = (unsigned char *)state->buff;
 	    }
 	  else
 	    {
-	      /* plain data preceding a domain-name, don't run off the end of the data */
-	      if ((state->end - state->ip) < d)
-		d = state->end - state->ip;
-	      
-	      if (d == 0)
-		continue;
-		  
+	      /* Plain data preceding a domain-name.
+		 Handle short RR, if there are no bytes left, return finished. */
+	      if ((state->end - state->ip) < d &&
+		  (d = state->end - state->ip) == 0)
+		return 0;
+				  
 	      state->op = state->ip;
 	      state->c = d;
 	      state->ip += d;

src/option.c

@@ -6270,7 +6270,11 @@ void read_opts(int argc, char **argv, char *compile_opts)
 	  
 	  if ((token = strtok(NULL, " \t\n\r")) &&  
 	      (daemon->domain_suffix = canonicalise_opt(token)))
-	    break;
+	    {
+	      /* We don't call get_line_alloc() until it returns false and frees the automatically */
+	      get_line_alloc(NULL, &line, &linesz);
+	      break;
+	    }
 	}
 
       fclose(f);

src/util.c

@@ -947,7 +947,7 @@ int kernel_version(void)
 }
 #endif
 
-#define hash_ptr(x) (((unsigned int)(((char *)(x)) - ((char *)NULL))) & 0xffffff)
+#define hash_ptr(x) (((uintptr_t)(x)) & 0xffffff)
 
 void *whine_malloc_real(const char *func, unsigned int line, size_t size)
 {
@@ -1038,16 +1038,15 @@ void free_real(const char *func, unsigned int line, void *ptr)
 }
 
 /* get lines from f, expand buffer as required. Buffer is freed when
-   EOF reached and we return zero. */
+   EOF reached and we return zero. Buffer also freed if f == NULL. */
 int get_line_alloc(FILE *f, char **buffp, size_t *sizep)
 {
-  char c;
   size_t cnt = 0;
   char *buff = *buffp;
-  
-  while (1) {
-    c = getc(f);
 
+  while (1) {
+    int c = f ? getc(f) : EOF;
+        
     if (cnt == *sizep)
       {
 	void *new;
@@ -1081,6 +1080,8 @@ int get_line_alloc(FILE *f, char **buffp, size_t *sizep)
 	  return 1;
 
 	free(buff);
+	*buffp = NULL;
+	*sizep = 0;
 	return 0;
       }