Re: Fwd: New Defects reported by Coverity Scan for git

From: Brandon Williams <bmwill@google.com>
Date: Jul 18, 2017, 18:00 UTC
Message-ID: <20170718180057.GA22656@google.com>
In-Reply-To: <xmqqy3rleijv.fsf@gitster.mtv.corp.google.com>

On 07/18, Junio C Hamano wrote:

Show 24 quoted lines

> Stefan Beller <sbeller@google.com> writes:
> 
> >> I'd be more worried about segfault we seem to be getting only on
> >> Windows from this:
> >>
> >>     git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules HEAD^ > actual
> >>
> >> in https://travis-ci.org/git/git/jobs/254654195 by the way.
> >
> > Thanks for bringing that to my attention, (I do not follow the travis builds
> > as closely, as there is no yelling email in my inbox).
> >
> > Windows builds on travis seem to be flaky.
> > (sometimes they do not start), but there are also
> > successful builds, including the -rc0, which may indicate
> > bw/grep-recurse-submodules may be faulty on Windows.
> 
> I can get valgrind complaints locally from
> 
>     $ cd t && sh t7814-grep*.sh --valgrind -i -v
> 
> so this may not be Windows only.  Can repo_worktree_path() return a NULL
> in repo_read_gitmodules() to cause git_config_from_file() barf on a NULL
> gitmodule_path?

Yep that's most likely the cause. The issue is if a repository doesn't have a worktree then what should a worktree path look like? repo_read_gitmodules() should check if there is a worktree before trying to load the gitmodules file. I actually noticed this and have it fixed locally in another series I'm working on right now. Looks like I may have to get that change in first though. Thanks for finding this.

Show 17 quoted lines

> 
> ==20383== Syscall param open(filename) points to unaddressable byte(s)
> ==20383==    at 0x5153140: __open_nocancel (/build/eglibc-SvCtMH/eglibc-2.19/io/../sysdeps/unix/syscall-template.S:81)
> ==20383==    by 0x50DDED7: _IO_file_fopen@@GLIBC_2.2.5 (/build/eglibc-SvCtMH/eglibc-2.19/libio/fileops.c:228)
> ==20383==    by 0x50D23D3: __fopen_internal (/build/eglibc-SvCtMH/eglibc-2.19/libio/iofopen.c:90)
> ==20383==    by 0x569107: git_fopen (/home/gitster/git.git/compat/fopen.c:22)
> ==20383==    by 0x55B1ED: fopen_or_warn (/home/gitster/git.git/wrapper.c:439)
> ==20383==    by 0x4A2A32: git_config_from_file (/home/gitster/git.git/config.c:1442)
> ==20383==    by 0x540317: repo_read_gitmodules (/home/gitster/git.git/submodule.c:269)
> ==20383==    by 0x434389: grep_submodule (/home/gitster/git.git/builtin/grep.c:422)
> ==20383==    by 0x4348C8: grep_tree (/home/gitster/git.git/builtin/grep.c:580)
> ==20383==    by 0x434867: grep_tree (/home/gitster/git.git/builtin/grep.c:576)
> ==20383==    by 0x436034: cmd_grep (/home/gitster/git.git/builtin/grep.c:622)
> ==20383==    by 0x4063DC: handle_builtin (/home/gitster/git.git/git.c:330)
> ==20383==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
> 
>

-- 
Brandon Williams