@matheusbsbs / matheus-bagliano / commits / d0cf51e940

do_one_ref(): save and restore value of current_ref

If do_one_ref() is called recursively, then the inner call should not permanently overwrite the value stored in current_ref by the outer call. Aside from the tiny optimization loss, peel_ref() expects the value of current_ref not to change across a call to peel_entry(). But in the presence of replace references that assumption could be violated by a recursive call to do_one_ref: do_for_each_entry() do_one_ref() builtin/describe.c:get_name() peel_ref() peel_entry() peel_object () deref_tag_noverify() parse_object() lookup_replace_object() do_lookup_replace_object() prepare_replace_object() do_for_each_ref() do_for_each_entry() do_for_each_entry_in_dir() do_one_ref() The inner call to do_one_ref() was unconditionally setting current_ref to NULL when it was done, causing peel_ref() to perform an invalid memory access. So change do_one_ref() to save the old value of current_ref before overwriting it, and restore the old value afterward rather than setting it to NULL. Reported-by: Mantas Mikulėnas <grawity@gmail.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Michael Haggerty committed Jul 15, 2013 at 17:24 UTC d0cf51e9401b6486aaecfea5dc3b01c3bb00f271

1 file changed +5 -1

refs.c

+5 -1

@@ -630,7 +630,9 @@ struct ref_entry_cb {

630 static int do_one_ref(struct ref_entry *entry, void *cb_data)

631 {

632 struct ref_entry_cb *data = cb_data;

633 + struct ref_entry *old_current_ref;

634 int retval;

635 +

636 if (prefixcmp(entry->name, data->base))

637 return 0;

638

@@ -638,10 +640,12 @@ static int do_one_ref(struct ref_entry *entry, void *cb_data)

640 !ref_resolves_to_object(entry))

641 return 0;

642

643 + /* Store the old value, in case this is a recursive call: */

644 + old_current_ref = current_ref;

645 current_ref = entry;

646 retval = data->fn(entry->name + data->trim, entry->u.value.sha1,

647 entry->flag, data->cb_data);

644 - current_ref = NULL;

648 + current_ref = old_current_ref;

649 return retval;

650 }

651