Fix tstring length

The tstring area was being allocated without accounting for the NUL byte
at the end of strings.

The tstring reset code was calculating the allocation size per string at
every iteration rather than once.

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Eugene Loh <eugene.loh@oracle.com>

libdtrace/dt_bpf.c

@@ -295,22 +295,23 @@ dt_bpf_gmap_create(dtrace_hdl_t *dtp)
 	 *	- size of the DTrace machine state, rounded up to the nearest
 	 *	  multiple of 8
 	 *	- 8 bytes padding for trace buffer alignment purposes
-	 *	- maximum trace buffer record size, rounded up to the
+	 *	- maximum trace buffer record size, rounded up to the nearest
 	 *	  multiple of 8
 	 *	- the greater of:
 	 *		+ the maximum stack trace size
-	 *		+ four times the maximum string size (incl. length
-	 *		  and allowing round up to multiple of 8)
-	 *		  plus the maximum string size (to accomodate the BPF
-	 *		  verifier)
+	 *		+ DT_TSTRING_SLOTS times the maximum string size (plus
+	 *		  space for length and terminating '\0') rounded up to
+	 *		  the nearest multiple of 8),
+	 *		  plus the maximum string size plus space for '\0' (to
+	 *		  accomodate the BPF verifier)
 	 */
 	memsz = roundup(sizeof(dt_mstate_t), 8) +
 		8 +
 		roundup(dtp->dt_maxreclen, 8) +
 		MAX(sizeof(uint64_t) * dtp->dt_options[DTRACEOPT_MAXFRAMES],
 		    DT_TSTRING_SLOTS *
 			roundup(DT_STRLEN_BYTES +
-				dtp->dt_options[DTRACEOPT_STRSIZE], 8) +
+				dtp->dt_options[DTRACEOPT_STRSIZE] + 1, 8) +
 		    dtp->dt_options[DTRACEOPT_STRSIZE] + 1
 		);
 	if (create_gmap(dtp, "mem", BPF_MAP_TYPE_PERCPU_ARRAY,

libdtrace/dt_cg.c

@@ -806,18 +806,19 @@ dt_cg_tstring_reset(dtrace_hdl_t *dtp)
 {
 	int		i;
 	dt_tstring_t	*ts;
+	uint64_t	size = roundup(DT_STRLEN_BYTES +
+				       dtp->dt_options[DTRACEOPT_STRSIZE] + 1,
+				       8);
 
 	if (dtp->dt_tstrings == NULL) {
 		dtp->dt_tstrings = dt_calloc(dtp, DT_TSTRING_SLOTS,
-					    sizeof(dt_tstring_t));
+					     sizeof(dt_tstring_t));
 		if (dtp->dt_tstrings == NULL)
 			longjmp(yypcb->pcb_jmpbuf, EDT_NOMEM);
 
 		ts = dtp->dt_tstrings;
 		for (i = 0; i < DT_TSTRING_SLOTS; i++, ts++)
-			ts->offset = i *
-				roundup(DT_STRLEN_BYTES +
-					dtp->dt_options[DTRACEOPT_STRSIZE], 8);
+			ts->offset = i * size;
 	}
 
 	ts = dtp->dt_tstrings;