t5510: verify that D/F confusion cannot lead to an RCE

The most critical vulnerabilities in Git lead to a Remote Code Execution ("RCE"), i.e. the ability for an attacker to have malicious code being run as part of a Git operation that is not expected to run said code, such has hooks delivered as part of a `git clone`. A couple of parent commits ago, a bug was fixed that let Git be confused by the presence of a path `a-` to mistakenly assume that a directory `a/` can safely be created without removing an existing `a` that is a symbolic link. This bug did not represent an exploitable vulnerability on its own; Let's make sure it stays that way. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Johannes Schindelin committed Mar 24, 2024 at 14:13 UTC e4930e86c0d521aa6c3c3da9f590e852f6eeac21
1 file changed +24
t/t5510-fetch.sh
+24
index c0b745e33b..211afe13e9 100755 --- a/t/t5510-fetch.sh +++ b/t/t5510-fetch.sh @@ -1240,6 +1240,30 @@ EOF test_cmp fatal-expect fatal-actual ' +test_expect_success SYMLINKS 'clone does not get confused by a D/F conflict' ' + git init df-conflict && + ( + cd df-conflict && + ln -s .git a && + git add a && + test_tick && + git commit -m symlink && + test_commit a- && + rm a && + mkdir -p a/hooks && + write_script a/hooks/post-checkout <<-EOF && + echo WHOOPSIE >&2 + echo whoopsie >"$TRASH_DIRECTORY"/whoops + EOF + git add a/hooks/post-checkout && + test_tick && + git commit -m post-checkout + ) && + git clone df-conflict clone 2>err && + ! grep WHOOPS err && + test_path_is_missing whoops +' + . "$TEST_DIRECTORY"/lib-httpd.sh start_httpd