[PATCH] tag: refuse tag messages that contain NULs

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

This follows the paranoid spirit in 37576c1 (commit_tree(): refuse
commit messages that contain NULs - 2011-12-15) and stops users from
creating tags that contain NULs. If these tags are merged into a commit
as mergetag lines, they may break the commit header processing badly.

While at it, check for NULs in mergetag and gpgsig lines before
committing too.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/mktag.c |    3 +++
 builtin/tag.c   |    2 ++
 commit.c        |    2 ++
 t/t7004-tag.sh  |    4 ++++
 4 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/builtin/mktag.c b/builtin/mktag.c
index 640ab64..f51ce20 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -165,6 +165,9 @@ int cmd_mktag(int argc, const char **argv, const char *prefix)
 	if (verify_tag(buf.buf, buf.len) < 0)
 		die("invalid tag signature file");
 
+	if (memchr(buf.buf, '\0', buf.len))
+		die("a NUL byte in tag message not allowed.");
+
 	if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
 		die("unable to write tag file");
 
diff --git a/builtin/tag.c b/builtin/tag.c
index 31f02e8..e66811e 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -259,6 +259,8 @@ static int build_tag_object(struct strbuf *buf, int sign, unsigned char *result)
 {
 	if (sign && do_sign(buf) < 0)
 		return error(_("unable to sign the tag"));
+	if (memchr(buf->buf, '\0', buf->len))
+		return error("a NUL byte in tag message not allowed.");
 	if (write_sha1_file(buf->buf, buf->len, tag_type, result) < 0)
 		return error(_("unable to write tag file"));
 	return 0;
diff --git a/commit.c b/commit.c
index 4b39c19..545325f 100644
--- a/commit.c
+++ b/commit.c
@@ -1144,6 +1144,8 @@ int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
 		strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
 
 	while (extra) {
+		if (memchr(extra->value, '\0', extra->len))
+			return error("a NUL byte in commit header %s not allowed.", extra->key);
 		add_extra_header(&buffer, extra);
 		extra = extra->next;
 	}
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index e93ac73..8cb13e5 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -1269,4 +1269,8 @@ test_expect_success 'mixing incompatibles modes and options is forbidden' '
 	test_must_fail git tag -v -s
 '
 
+test_expect_success 'tag content contains NUL' '
+	test_must_fail git tag -F "$TEST_DIRECTORY"/t3900/UTF-16.txt utf16
+'
+
 test_done
-- 
1.7.8.36.g69ee2