Re: [PATCH v2 1/9] worktree: remove redundant NULL-ing of "cp.argv

On Wed, Nov 24, 2021 at 1:00 AM Eric Sunshine [off-list ref] wrote:

On Tue, Nov 23, 2021 at 8:54 PM Junio C Hamano [off-list ref] wrote:

quoted

Thanks for spotting this.  Has this patch ever been tested with
sanitizer?  Do we have gap in test coverage?

The question about potential gap in test coverage is a good one.
Maybe, by chance it reallocated the same memory that it had earlier
freed, thus did indeed work "by accident". Another possibility is that
Ævar only ran the tests after applying the full patch series, in which
case this dangling-pointer bug would be gone, rather than running the
tests after each patch.

As a follow-up, I just applied this patch alone and ran the tests, and
they do indeed fail as expected (on my macOS). In
t2400-worktree-add.sh, alone, 44 out of 71 tests failed, thus I don't
think there's a gap in test coverage. So, the most likely explanation
of how this problem slipped through is that Ævar only tested after
applying the full series, in which case the dangling pointer bug would
be gone, rather than testing after each patch.