Subject: [PATCH v2 1/3] merge-base, xdiff: zero out xpparam_t structures

From: Michał Kępień <[email-masked]>
Date: Mon, 12 Oct 2020 11:17:49 +0200

xpparam_t structures are usually zero-initialized before their specific
fields are assigned to, but there are three locations in the tree where
that does not happen.  Add the missing memset() calls in order to make
initialization of xpparam_t structures consistent tree-wide and to
prevent stack garbage from being used as field values.

Signed-off-by: Michał Kępień <[email-masked]>
---
 builtin/merge-tree.c | 1 +
 xdiff/xhistogram.c   | 2 ++
 xdiff/xpatience.c    | 2 ++
 3 files changed, 5 insertions(+)

diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index e72714a5a8..de8520778d 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -109,6 +109,7 @@ static void show_diff(struct merge_list *entry)
 	xdemitconf_t xecfg;
 	xdemitcb_t ecb;
 
+	memset(&xpp, 0, sizeof(xpp));
 	xpp.flags = 0;
 	memset(&xecfg, 0, sizeof(xecfg));
 	xecfg.ctxlen = 3;
diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c
index c7b35a9667..e694bfd9e3 100644
--- a/xdiff/xhistogram.c
+++ b/xdiff/xhistogram.c
@@ -235,6 +235,8 @@ static int fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env,
 		int line1, int count1, int line2, int count2)
 {
 	xpparam_t xpparam;
+
+	memset(&xpparam, 0, sizeof(xpparam));
 	xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
 
 	return xdl_fall_back_diff(env, &xpparam,
diff --git a/xdiff/xpatience.c b/xdiff/xpatience.c
index 3c5601b602..20699a6f60 100644
--- a/xdiff/xpatience.c
+++ b/xdiff/xpatience.c
@@ -318,6 +318,8 @@ static int fall_back_to_classic_diff(struct hashmap *map,
 		int line1, int count1, int line2, int count2)
 {
 	xpparam_t xpp;
+
+	memset(&xpp, 0, sizeof(xpp));
 	xpp.flags = map->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
 
 	return xdl_fall_back_diff(map->env, &xpp,
-- 
2.28.0