In diff_tree_combined we make a copy of diffopts. In
try_to_follow_renames, called via diff_tree_sha1, we free and
re-initialize diffopts->pathspec->items. Since we did not make a deep
copy of diffopts in diff_tree_combined, the original diffopts does not
get the update. By the time we return from diff_tree_combined,
rev->diffopt->pathspec->items points to an invalid memory address. We
get a segfault next time we try to access that pathspec.

Instead, along with the copy of diffopts, make a copy pathspec->items as

We would also have to make a copy of pathspec->raw to keep it consistent
with pathspec->items, but nobody seems to rely on that.

Signed-off-by: Clemens Buchacher <>

I wonder why I get a segfault from this so reliably, since it's not
actually a null-pointer dereference. Maybe this is gcc 4.8 doing
something different from previous versions?

Also, I have absolutely no confidence in my understanding of this code.
This is the first solution that came to mind, and could be totally
wrong. I just figured a patch is better than no patch.


 combine-diff.c |  3 +++
 t/ | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/combine-diff.c b/combine-diff.c
index 77d7872..8825604 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -1302,6 +1302,7 @@ void diff_tree_combined(const unsigned char *sha1,
        int i, num_paths, needsep, show_log_first, num_parent = parents->nr;
        diffopts = *opt;
+       diff_tree_setup_paths(diffopts.pathspec.raw, &diffopts);
        diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
        DIFF_OPT_SET(&diffopts, RECURSIVE);
        DIFF_OPT_CLR(&diffopts, ALLOW_EXTERNAL);
@@ -1372,6 +1373,8 @@ void diff_tree_combined(const unsigned char *sha1,
                paths = paths->next;
+       diff_tree_release_paths(&diffopts);
 void diff_tree_combined_merge(const struct commit *commit, int dense,
diff --git a/t/ b/t/
index 9243a97..cb03d28 100755
--- a/t/
+++ b/t/
@@ -530,6 +530,20 @@ test_expect_success 'show added path under "--follow -M"' '
+test_expect_success 'git log -c --follow' '
+       test_create_repo follow-c &&
+       (
+               cd follow-c &&
+               test_commit initial file original &&
+               git rm file &&
+               test_commit rename file2 original &&
+               git reset --hard initial &&
+               test_commit modify file foo &&
+               git merge -m merge rename &&
+               git log -c --follow file2
+       )
 cat >expect <<\EOF

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