From d0cf51e9401b6486aaecfea5dc3b01c3bb00f271 Mon Sep 17 00:00:00 2001
From: Michael Haggerty <mhagger@alum.mit.edu>
Date: Mon, 15 Jul 2013 17:24:17 +0200
Subject: [PATCH] do_one_ref(): save and restore value of current_ref
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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>
---
refs.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/refs.c b/refs.c
index d17931a8bc..f8ad1d608c 100644
--- a/refs.c
+++ b/refs.c
@@ -630,7 +630,9 @@ struct ref_entry_cb {
static int do_one_ref(struct ref_entry *entry, void *cb_data)
{
struct ref_entry_cb *data = cb_data;
+ struct ref_entry *old_current_ref;
int retval;
+
if (prefixcmp(entry->name, data->base))
return 0;
@@ -638,10 +640,12 @@ static int do_one_ref(struct ref_entry *entry, void *cb_data)
!ref_resolves_to_object(entry))
return 0;
+ /* Store the old value, in case this is a recursive call: */
+ old_current_ref = current_ref;
current_ref = entry;
retval = data->fn(entry->name + data->trim, entry->u.value.sha1,
entry->flag, data->cb_data);
- current_ref = NULL;
+ current_ref = old_current_ref;
return retval;
}