From 000c4ceca794645eb4744f9c9afb6247232c0646 Mon Sep 17 00:00:00 2001 From: Elijah Newren 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)); 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 Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano --- 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_*() ***/