Subject: [PATCH 0/7] harden unexpected object types checks

From: Taylor Blau <[email-masked]>
Date: Thu, 4 Apr 2019 20:37:39 -0700

Hi everybody,

Peff pointed out to me a couple of weeks ago that we could reproducibly
crash Git when doing the following:

  $ git rev-list --objects <blob> <broken-tree>

Where <blob> is a normal blob, and <broken-tree> is a tree which
contains an entry that refers to <blob> but gives it a type other than
'blob'. (This is described in detail in 2/7 and fixed in 3/7.)

We decided to continue, trying to come up with more tests that exercise
similar object corruption, and the tests
't6102-rev-list-unexpected-objects.sh' are what we came up with.

The series goes as follows:

  1. Prepare ourselves by moving a helper in 't' into
     test-lib-functions.sh so that we can use it in a new location.

  2. Write out a handful of tests that exercises cases similar to the
     above, and mark the ones with bugs as 'test_expect_failure'.

  3. Fix (most) of them in each subsequent commit.

The exception we make for step (3) is that don't provide a complete fix,
only restore behavior to before the commit at which it regressed.

I'll be brief here, since most of the detail is described at length in
the patches themselves. This said, please do ask questions where I
wasn't clear, or could have been clearer. (This series grew larger than
I originally expected it to, so perhaps there is detail that I
accumulated and didn't devote enough time to).

Thanks as always in advance for your review.

Jeff King (3):
  get_commit_tree(): return NULL for broken tree
  rev-list: let traversal die when --missing is not in use
  rev-list: detect broken root trees

Taylor Blau (4):
  t: move 'hex2oct' into test-lib-functions.sh
  t: introduce tests for unexpected object types
  list-objects.c: handle unexpected non-blob entries
  list-objects.c: handle unexpected non-tree entries

 builtin/rev-list.c                     |   4 +-
 commit.c                               |   6 +-
 list-objects.c                         |  13 +++
 t/t1007-hash-object.sh                 |   4 -
 t/t1450-fsck.sh                        |   4 -
 t/t5601-clone.sh                       |   4 -
 t/t6102-rev-list-unexpected-objects.sh | 127 +++++++++++++++++++++++++
 t/test-lib-functions.sh                |   6 ++
 8 files changed, 152 insertions(+), 16 deletions(-)
 create mode 100755 t/t6102-rev-list-unexpected-objects.sh

--
2.21.0.203.g358da99528