Sync with 2.16.6

* maint-2.16: (31 commits)
  Git 2.16.6
  test-drop-caches: use `has_dos_drive_prefix()`
  Git 2.15.4
  Git 2.14.6
  mingw: handle `subst`-ed "DOS drives"
  mingw: refuse to access paths with trailing spaces or periods
  mingw: refuse to access paths with illegal characters
  unpack-trees: let merged_entry() pass through do_add_entry()'s errors
  quote-stress-test: offer to test quoting arguments for MSYS2 sh
  t6130/t9350: prepare for stringent Win32 path validation
  quote-stress-test: allow skipping some trials
  quote-stress-test: accept arguments to test via the command-line
  tests: add a helper to stress test argument quoting
  mingw: fix quoting of arguments
  Disallow dubiously-nested submodule git directories
  protect_ntfs: turn on NTFS protection by default
  path: also guard `.gitmodules` against NTFS Alternate Data Streams
  is_ntfs_dotgit(): speed it up
  mingw: disallow backslash characters in tree objects' file names
  path: safeguard `.git` against NTFS Alternate Streams Accesses
  ...

Documentation/RelNotes/2.14.6.txt

@@ -0,0 +1,54 @@
+Git v2.14.6 Release Notes
+=========================
+
+This release addresses the security issues CVE-2019-1348,
+CVE-2019-1349, CVE-2019-1350, CVE-2019-1351, CVE-2019-1352,
+CVE-2019-1353, CVE-2019-1354, and CVE-2019-1387.
+
+Fixes since v2.14.5
+-------------------
+
+ * CVE-2019-1348:
+   The --export-marks option of git fast-import is exposed also via
+   the in-stream command feature export-marks=... and it allows
+   overwriting arbitrary paths.
+
+ * CVE-2019-1349:
+   When submodules are cloned recursively, under certain circumstances
+   Git could be fooled into using the same Git directory twice. We now
+   require the directory to be empty.
+
+ * CVE-2019-1350:
+   Incorrect quoting of command-line arguments allowed remote code
+   execution during a recursive clone in conjunction with SSH URLs.
+
+ * CVE-2019-1351:
+   While the only permitted drive letters for physical drives on
+   Windows are letters of the US-English alphabet, this restriction
+   does not apply to virtual drives assigned via subst <letter>:
+   <path>. Git mistook such paths for relative paths, allowing writing
+   outside of the worktree while cloning.
+
+ * CVE-2019-1352:
+   Git was unaware of NTFS Alternate Data Streams, allowing files
+   inside the .git/ directory to be overwritten during a clone.
+
+ * CVE-2019-1353:
+   When running Git in the Windows Subsystem for Linux (also known as
+   "WSL") while accessing a working directory on a regular Windows
+   drive, none of the NTFS protections were active.
+
+ * CVE-2019-1354:
+   Filenames on Linux/Unix can contain backslashes. On Windows,
+   backslashes are directory separators. Git did not use to refuse to
+   write out tracked files with such filenames.
+
+ * CVE-2019-1387:
+   Recursive clones are currently affected by a vulnerability that is
+   caused by too-lax validation of submodule names, allowing very
+   targeted attacks via remote code execution in recursive clones.
+
+Credit for finding these vulnerabilities goes to Microsoft Security
+Response Center, in particular to Nicolas Joly. The `fast-import`
+fixes were provided by Jeff King, the other fixes by Johannes
+Schindelin with help from Garima Singh.

Documentation/RelNotes/2.15.4.txt

@@ -0,0 +1,11 @@
+Git v2.15.4 Release Notes
+=========================
+
+This release merges up the fixes that appear in v2.14.6 to address
+the security issues CVE-2019-1348, CVE-2019-1349, CVE-2019-1350,
+CVE-2019-1351, CVE-2019-1352, CVE-2019-1353, CVE-2019-1354, and
+CVE-2019-1387; see the release notes for that version for details.
+
+In conjunction with a vulnerability that was fixed in v2.20.2,
+`.gitmodules` is no longer allowed to contain entries of the form
+`submodule.<name>.update=!command`.

Documentation/RelNotes/2.16.6.txt

@@ -0,0 +1,8 @@
+Git v2.16.6 Release Notes
+=========================
+
+This release merges up the fixes that appear in v2.14.6 and in
+v2.15.4 addressing the security issues CVE-2019-1348, CVE-2019-1349,
+CVE-2019-1350, CVE-2019-1351, CVE-2019-1352, CVE-2019-1353,
+CVE-2019-1354, and CVE-2019-1387; see the release notes for those
+versions for details.

Documentation/git-fast-import.txt

@@ -50,6 +50,21 @@ OPTIONS
 	memory used by fast-import during this run.  Showing this output
 	is currently the default, but can be disabled with --quiet.
 
+--allow-unsafe-features::
+	Many command-line options can be provided as part of the
+	fast-import stream itself by using the `feature` or `option`
+	commands. However, some of these options are unsafe (e.g.,
+	allowing fast-import to access the filesystem outside of the
+	repository). These options are disabled by default, but can be
+	allowed by providing this option on the command line.  This
+	currently impacts only the `export-marks`, `import-marks`, and
+	`import-marks-if-exists` feature commands.
++
+	Only enable this option if you trust the program generating the
+	fast-import stream! This option is enabled automatically for
+	remote-helpers that use the `import` capability, as they are
+	already trusted to run their own code.
+
 Options for Frontends
 ~~~~~~~~~~~~~~~~~~~~~
 

Documentation/gitmodules.txt

@@ -44,9 +44,8 @@ submodule.<name>.update::
 	submodule init` to initialize the configuration variable of
 	the same name. Allowed values here are 'checkout', 'rebase',
 	'merge' or 'none'. See description of 'update' command in
-	linkgit:git-submodule[1] for their meaning. Note that the
-	'!command' form is intentionally ignored here for security
-	reasons.
+	linkgit:git-submodule[1] for their meaning. For security
+	reasons, the '!command' form is not accepted here.
 
 submodule.<name>.branch::
 	A remote branch name for tracking updates in the upstream submodule.