Fix ssl3_write_pending, BIO_write returns 0 is considered a success

Tongsuo-Project · Jun 27, 2024 · e4f070e · e4f070e
1 parent 8a971f9
commit e4f070e
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/ssl/record/rec_layer_s3.c b/ssl/record/rec_layer_s3.c
@@ -1160,7 +1160,13 @@ int ssl3_write_pending(SSL *s, int type, const unsigned char *buf, size_t len,
                      SSL_R_BIO_NOT_SET);
             i = -1;
         }
-        if (i > 0 && tmpwrit == SSL3_BUFFER_get_left(&wb[currbuf])) {
+
+        /*
+         * If zero byte write succeeds, i will be 0 rather than a non-zero
+         * value. Treat i == 0 as success rather than an error for zero byte
+         * writes to permit this case.
+         */
+        if (i >= 0 && tmpwrit == SSL3_BUFFER_get_left(&wb[currbuf])) {
             SSL3_BUFFER_set_left(&wb[currbuf], 0);
             SSL3_BUFFER_add_offset(&wb[currbuf], tmpwrit);
             if (currbuf + 1 < s->rlayer.numwpipes)