krb5 commit [krb5-1.13]: Fix incorrect recv() size calculation in libkrad

[Tom Yu]

https://github.com/krb5/krb5/commit/5b8dab42d541d2600c76647dedf56251f7f9da33
commit 5b8dab42d541d2600c76647dedf56251f7f9da33
Author: Nathaniel McCallum <npmccallum at redhat.com>
Date:   Tue Jun 21 16:12:36 2016 -0400

    Fix incorrect recv() size calculation in libkrad
    
    Before this patch libkrad would always subtract the existing buffer
    length from pktlen before passing it to recv().  In the case of stream
    sockets, this is incorrect since krad_packet_bytes_needed() already
    performs this calculation.  Subtracting the buffer length twice could
    cause integer underflow on the len parameter to recv().
    
    (cherry picked from commit c969e8a37617e9c7743a28177dd3808f7d08cee9)
    
    ticket: 8430
    version_fixed: 1.13.6
    tags: -pullup
    status: resolved

 src/lib/krad/remote.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib/krad/remote.c b/src/lib/krad/remote.c
index aaabffd..df3de3a 100644
--- a/src/lib/krad/remote.c
+++ b/src/lib/krad/remote.c
@@ -315,7 +315,7 @@ on_io_read(krad_remote *rr)
     request *tmp, *r;
     int i;
 
-    pktlen = sizeof(rr->buffer_);
+    pktlen = sizeof(rr->buffer_) - rr->buffer.length;
     if (rr->info->ai_socktype == SOCK_STREAM) {
         pktlen = krad_packet_bytes_needed(&rr->buffer);
         if (pktlen < 0) {
@@ -328,7 +328,7 @@ on_io_read(krad_remote *rr)
 
     /* Read the packet. */
     i = recv(verto_get_fd(rr->io), rr->buffer.data + rr->buffer.length,
-             pktlen - rr->buffer.length, 0);
+             pktlen, 0);
     if (i < 0) {
         /* Should we try again? */
         if (errno == EWOULDBLOCK || errno == EAGAIN || errno == EINTR)