From 000c4ceca794645eb4744f9c9afb6247232c0646 Mon Sep 17 00:00:00 2001
From: Elijah Newren <newren@gmail.com>
Date: Sat, 22 Apr 2023 20:22:10 +0000
Subject: [PATCH] merge-ort: fix calling merge_finalize() with no intermediate
merge
If some code sets up the data structures for a merge, but then never
actually performs one before calling merge_finalize(), then
merge_finalize() wouldn't notice that result->priv was NULL and
return early, resulting in following that NULL pointer and getting
a segfault. There is currently no code in the git codebase that does
this, but this issue was found during testing of some proposed patches
that had the following structure:
struct merge_options merge_opt;
struct merge_result result;
init_merge_options(&merge_opt, the_repository);
memset(&result, 0, sizeof(result));
<do N merges, for some value of N>
merge_finalize(&merge_opt, &result);
where some flags could cause the code to have N=0, i.e. doing no merges.
Add a check for result->priv being NULL and return early to avoid a
segfault in these kinds of cases.
While at it, ensure the FREE_AND_NULL() in the function does something
useful with the nulling aspect, namely sets result->priv to NULL rather
than a mere temporary.
Reported-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
merge-ort.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/merge-ort.c b/merge-ort.c
index e5f41cce48..36a140f8ed 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -4683,14 +4683,14 @@ void merge_switch_to_result(struct merge_options *opt,
void merge_finalize(struct merge_options *opt,
struct merge_result *result)
{
- struct merge_options_internal *opti = result->priv;
-
if (opt->renormalize)
git_attr_set_direction(GIT_ATTR_CHECKIN);
assert(opt->priv == NULL);
- clear_or_reinit_internal_opts(opti, 0);
- FREE_AND_NULL(opti);
+ if (result->priv) {
+ clear_or_reinit_internal_opts(result->priv, 0);
+ FREE_AND_NULL(result->priv);
+ }
}
/*** Function Grouping: helper functions for merge_incore_*() ***/