1 files changed, 1 insertions, 0 deletions

diff --git a/src/lib/libcrypto/evp/bio_b64.c b/src/lib/libcrypto/evp/bio_b64.c
index f12eac1b55..6e550f6a43 100644
--- a/src/lib/libcrypto/evp/bio_b64.c
+++ b/src/lib/libcrypto/evp/bio_b64.c
@@ -165,6 +165,7 @@ static int b64_read(BIO *b, char *out, int outl)
                 {
                 i=ctx->buf_len-ctx->buf_off;
                 if (i > outl) i=outl;
+                OPENSSL_assert(ctx->buf_off+i < sizeof ctx->buf);
                 memcpy(out,&(ctx->buf[ctx->buf_off]),i);
                 ret=i;
                 out+=i;