Merge branch 'ps/build-sign-compare'

Last-minute fix for a regression in "git blame --abbrev=<length>"
when insane <length> is specified; we used to correctly cap it to
the hash output length but broke it during the cycle.

* ps/build-sign-compare:
  builtin/blame: fix out-of-bounds write with blank boundary commits
  builtin/blame: fix out-of-bounds read with excessive `--abbrev`

Author: gitster

builtin/blame.c

@@ -489,9 +489,9 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 			fputs(color, stdout);
 
 		if (suspect->commit->object.flags & UNINTERESTING) {
-			if (blank_boundary)
-				memset(hex, ' ', length);
-			else if (!(opt & OUTPUT_ANNOTATE_COMPAT)) {
+			if (blank_boundary) {
+				memset(hex, ' ', strlen(hex));
+			} else if (!(opt & OUTPUT_ANNOTATE_COMPAT)) {
 				length--;
 				putchar('^');
 			}
@@ -505,7 +505,8 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 			length--;
 			putchar('?');
 		}
-		fwrite(hex, 1, length, stdout);
+
+		printf("%.*s", (int)(length < GIT_MAX_HEXSZ ? length : GIT_MAX_HEXSZ), hex);
 		if (opt & OUTPUT_ANNOTATE_COMPAT) {
 			const char *name;
 			if (opt & OUTPUT_SHOW_EMAIL)

t/t8002-blame.sh

@@ -126,6 +126,32 @@ test_expect_success '--no-abbrev works like --abbrev with full length' '
 	check_abbrev $hexsz --no-abbrev
 '
 
+test_expect_success 'blame --abbrev gets truncated' '
+	check_abbrev $hexsz --abbrev=9000 HEAD
+'
+
+test_expect_success 'blame --abbrev gets truncated with boundary commit' '
+	check_abbrev $hexsz --abbrev=9000 ^HEAD
+'
+
+test_expect_success 'blame --abbrev -b truncates the blank boundary' '
+	# Note that `--abbrev=` always gets incremented by 1, which is why we
+	# expect 11 leading spaces and not 10.
+	cat >expect <<-EOF &&
+	$(printf "%0.s " $(test_seq 11)) (<[email protected]> 2005-04-07 15:45:13 -0700 1) abbrev
+	EOF
+	git blame -b --abbrev=10 ^HEAD -- abbrev.t >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'blame with excessive --abbrev and -b culls to hash length' '
+	cat >expect <<-EOF &&
+	$(printf "%0.s " $(test_seq $hexsz)) (<[email protected]> 2005-04-07 15:45:13 -0700 1) abbrev
+	EOF
+	git blame -b --abbrev=9000 ^HEAD -- abbrev.t >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success '--exclude-promisor-objects does not BUG-crash' '
 	test_must_fail git blame --exclude-promisor-objects one
 '