Fix the BIO callback return code handling

The BIO callback handling incorrectly wrote over the return code passed
to the callback, meaning that an incorrect result was (eventually) returned
to the caller.

Fixes #7343

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7344)

diff --git a/crypto/bio/bio_lib.c b/crypto/bio/bio_lib.c
index 95eef7d4bf5b85da2a2ba46f0887fd2577bea64d..ca375b911ae8b510b39c0456f90b897a3aff6756 100644 (file)
--- a/crypto/bio/bio_lib.c
+++ b/crypto/bio/bio_lib.c
@@ -52,7 +52,7 @@ static long bio_call_callback(BIO *b, int oper, const char *argp, size_t len,
         argi = (int)len;
     }
 
-    if (inret && (oper & BIO_CB_RETURN) && bareoper != BIO_CB_CTRL) {
+    if (inret > 0 && (oper & BIO_CB_RETURN) && bareoper != BIO_CB_CTRL) {
         if (*processed > INT_MAX)
             return -1;
         inret = *processed;
@@ -60,7 +60,7 @@ static long bio_call_callback(BIO *b, int oper, const char *argp, size_t len,
 
     ret = b->callback(b, oper, argp, argi, argl, inret);
 
-    if (ret >= 0 && (oper & BIO_CB_RETURN) && bareoper != BIO_CB_CTRL) {
+    if (ret > 0 && (oper & BIO_CB_RETURN) && bareoper != BIO_CB_CTRL) {
         *processed = (size_t)ret;
         ret = 1;
     }