From f5fc30a1ef490079102d96ccc6d883f933be23c2 Mon Sep 17 00:00:00 2001
From: Zoltan Fridrich <zfridric@redhat.com>
Date: Sat, 24 Sep 2022 10:56:31 +0200
Subject: [PATCH] Avoid calling hash update with NULL input (and zero length)

---
 balloon.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/balloon.c b/balloon.c
index 75240ab4..d135ee86 100644
--- a/balloon.c
+++ b/balloon.c
@@ -61,8 +61,10 @@ hash(void *ctx,
   uint8_t tmp[8];
   LE_WRITE_UINT64(tmp, cnt);
   update(ctx, sizeof(tmp), tmp);
-  update(ctx, a_len, a);
-  update(ctx, b_len, b);
+  if (a && a_len)
+    update(ctx, a_len, a);
+  if (b && b_len)
+    update(ctx, b_len, b);
   digest(ctx, digest_size, dst);
 }
 
-- 
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