From 4ee90fe0e626c5d7ed06f803ff3a4470172659ac Mon Sep 17 00:00:00 2001
From: Ben Taylor <32939606+bjwtaylor@users.noreply.github.com>
Date: Wed, 10 Jun 2026 07:48:55 +0100
Subject: [PATCH] Correct logic for keystream_bytes_used

Co-authored-by: minosgalanakis <30719586+minosgalanakis@users.noreply.github.com>
Signed-off-by: Ben Taylor <32939606+bjwtaylor@users.noreply.github.com>
(cherry picked from commit 8de9f6aa776d5e92d77b10dfca6666f83f542ab2)
---
 library/chacha20.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/chacha20.c b/library/chacha20.c
index 53bf4900b6..41383c44b2 100644
--- a/library/chacha20.c
+++ b/library/chacha20.c
@@ -210,7 +210,7 @@ int mbedtls_chacha20_check_counter_wrap(const mbedtls_chacha20_context *ctx,
     size_t available_keystream = 0;
     uint64_t needed_blocks = 0;
 
-    if (ctx->keystream_bytes_used == CHACHA20_COUNTER_EXHAUSTED) {
+    if (ctx->keystream_bytes_used >= CHACHA20_COUNTER_EXHAUSTED) {
         return size == 0U ? 0 : MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA;
     }