From 19136be3f874ac265195ef35a8c5ed6c417eaea2 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Wed, 24 Jan 2018 19:56:07 -0500 Subject: [PATCH] daemon: fix off-by-one in logging extended attributes If receive a request like: git-upload-pack /foo.git\0host=localhost we mark the offset of the NUL byte as "len", and then log the bytes after the NUL with a "%.*s" placeholder, using "pktlen - len" as the length, and "line + len + 1" as the start of the string. This is off-by-one, since the start of the string skips past the separating NUL byte, but the adjusted length includes it. Fortunately this doesn't actually read past the end of the buffer, since "%.*s" will stop when it hits a NUL. And regardless of what is in the buffer, packet_read() will always add an extra NUL terminator for safety. As an aside, the git.git client sends an extra NUL after a "host" field, too, so we'd generally hit that one first, not the one added by packet_read(). You can see this in the test output which reports 15 bytes, even though the string has only 14 bytes of visible data. But the point is that even a client sending unusual data could not get us to read past the end of the buffer, so this is purely a cosmetic fix. Reported-by: Michael Haggerty Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- daemon.c | 4 ++-- t/t5570-git-daemon.sh | 11 +++++++++++ 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/daemon.c b/daemon.c index e37e343d0a..d78afc8e96 100644 --- a/daemon.c +++ b/daemon.c @@ -759,8 +759,8 @@ static int execute(void) len = strlen(line); if (pktlen != len) loginfo("Extended attributes (%d bytes) exist <%.*s>", - (int) pktlen - len, - (int) pktlen - len, line + len + 1); + (int) pktlen - len - 1, + (int) pktlen - len - 1, line + len + 1); if (len && line[len-1] == '\n') { line[--len] = 0; pktlen--; diff --git a/t/t5570-git-daemon.sh b/t/t5570-git-daemon.sh index f92ebc5cd5..359af3994a 100755 --- a/t/t5570-git-daemon.sh +++ b/t/t5570-git-daemon.sh @@ -183,5 +183,16 @@ test_expect_success 'hostname cannot break out of directory' ' git ls-remote "$GIT_DAEMON_URL/escape.git" ' +test_expect_success 'daemon log records hostnames' ' + cat >expect <<-\EOF && + Extended attributes (15 bytes) exist + EOF + >daemon.log && + GIT_OVERRIDE_VIRTUAL_HOST=localhost \ + git ls-remote "$GIT_DAEMON_URL/interp.git" && + grep -i extended.attribute daemon.log | cut -d" " -f2- >actual && + test_cmp expect actual +' + stop_git_daemon test_done