[PATCH] commit-reach: fix sorting commits by generation
- From
Thomas Gummerer <t.gummerer@gmail.com>
- Date
- Oct 22, 2018, 21:10 UTC
- Message-ID
- <20181022211037.22719-1-t.gummerer@gmail.com>
compare_commit_by_gen is used to sort a list of pointers to 'struct commit'. The comparison function for qsort is called with pointers to the objects it needs to compare, so when sorting a list of 'struct commit *', the arguments are of type 'struct commit **'. However, currently the comparison function casts it's arguments to 'struct commit *' and uses those, leading to out of bounds memory access and potentially to wrong results. Fix that.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com> ---
I noticed this by running the test suite through valgrind. I'm not familiar with this code, so I'm not sure why this didn't cause any issues or how they would manifest, but this seems like the right fix for this function either way.
commit-reach.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/commit-reach.c b/commit-reach.c index bc522d6840..9efddfd7a0 100644 --- a/commit-reach.c +++ b/commit-reach.c @@ -516,8 +516,8 @@ int commit_contains(struct ref_filter *filter, struct commit *commit, static int compare_commits_by_gen(const void *_a, const void *_b) { - const struct commit *a = (const struct commit *)_a; - const struct commit *b = (const struct commit *)_b; + const struct commit *a = *(const struct commit **)_a; + const struct commit *b = *(const struct commit **)_b; if (a->generation < b->generation) return -1;
-- 2.19.1.759.g500967bb5e