git: b1902474a7c5 - stable/12 - sbin/ipfw: Fix null pointer deference when printing counters

[Lutz Donnerhacke]

The branch stable/12 has been updated by donner:

URL: https://cgit.FreeBSD.org/src/commit/?id=b1902474a7c51e025d734e8233f0e850291b92e7

commit b1902474a7c51e025d734e8233f0e850291b92e7
Author:     Lutz Donnerhacke <donner at FreeBSD.org>
AuthorDate: 2021-05-09 12:48:47 +0000
Commit:     Lutz Donnerhacke <donner at FreeBSD.org>
CommitDate: 2021-05-09 12:48:47 +0000

    sbin/ipfw: Fix null pointer deference when printing counters
    
    ipfw -[tT] prints statistics of the last access. If the rule was never
    used, the counter might be not exist.  This happens unconditionally on
    inserting a new rule.  Avoid printing statistics in this case.
    
    PR:             255491
    Reported by:    Haisheng Zhouz
    Reviewed by:    ae
    Differential Revision:  https://reviews.freebsd.org/D30046
    
    (cherry picked from commit bf7cc0f9cb6603a6bdd6131c8d1939724ce6e62d)
---
 sbin/ipfw/ipfw2.c | 51 +++++++++++++++++++++++++++------------------------
 1 file changed, 27 insertions(+), 24 deletions(-)

diff --git a/sbin/ipfw/ipfw2.c b/sbin/ipfw/ipfw2.c
index 30a4da92343f..efb29403b6c9 100644
--- a/sbin/ipfw/ipfw2.c
+++ b/sbin/ipfw/ipfw2.c
@@ -2174,32 +2174,35 @@ show_static_rule(struct cmdline_opts *co, struct format_opts *fo,
 	}
 	bprintf(bp, "%05u ", rule->rulenum);
 
-	/* Print counters if enabled */
-	if (fo->pcwidth > 0 || fo->bcwidth > 0) {
-		pr_u64(bp, &cntr->pcnt, fo->pcwidth);
-		pr_u64(bp, &cntr->bcnt, fo->bcwidth);
-	}
-
-	/* Print timestamp */
-	if (co->do_time == TIMESTAMP_NUMERIC)
-		bprintf(bp, "%10u ", cntr->timestamp);
-	else if (co->do_time == TIMESTAMP_STRING) {
-		char timestr[30];
-		time_t t = (time_t)0;
-
-		if (twidth == 0) {
-			strcpy(timestr, ctime(&t));
-			*strchr(timestr, '\n') = '\0';
-			twidth = strlen(timestr);
+	/* only if counters are available */
+	if (cntr != NULL) {
+		/* Print counters if enabled */
+		if (fo->pcwidth > 0 || fo->bcwidth > 0) {
+			pr_u64(bp, &cntr->pcnt, fo->pcwidth);
+			pr_u64(bp, &cntr->bcnt, fo->bcwidth);
 		}
-		if (cntr->timestamp > 0) {
-			t = _long_to_time(cntr->timestamp);
 
-			strcpy(timestr, ctime(&t));
-			*strchr(timestr, '\n') = '\0';
-			bprintf(bp, "%s ", timestr);
-		} else {
-			bprintf(bp, "%*s", twidth + 1, " ");
+		/* Print timestamp */
+		if (co->do_time == TIMESTAMP_NUMERIC)
+			bprintf(bp, "%10u ", cntr->timestamp);
+		else if (co->do_time == TIMESTAMP_STRING) {
+			char timestr[30];
+			time_t t = (time_t)0;
+
+			if (twidth == 0) {
+				strcpy(timestr, ctime(&t));
+				*strchr(timestr, '\n') = '\0';
+				twidth = strlen(timestr);
+			}
+			if (cntr->timestamp > 0) {
+				t = _long_to_time(cntr->timestamp);
+
+				strcpy(timestr, ctime(&t));
+				*strchr(timestr, '\n') = '\0';
+				bprintf(bp, "%s ", timestr);
+			} else {
+				bprintf(bp, "%*s", twidth + 1, " ");
+			}
 		}
 	}