From: Josh Durgin <josh.durgin@dreamhost.com>
Date: Fri, 23 Sep 2011 21:04:14 +0000 (-0700)
Subject: librbd: don't zero negative lengths
X-Git-Tag: v0.36~5
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=1e4fdf510c2d891ea0a46d7c194fbc3b37c981bd;p=ceph.git

librbd: don't zero negative lengths

They are past the end of the buffer (and wrap around).

Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>
---

diff --git a/src/librbd.cc b/src/librbd.cc
index e102c5e5b5f..b5ae4b18495 100644
--- a/src/librbd.cc
+++ b/src/librbd.cc
@@ -1377,7 +1377,7 @@ ssize_t handle_sparse_read(CephContext *cct,
     ldout(cct, 10) << "block_ofs=" << block_ofs << dendl;
 
     /* a hole? */
-    if (extent_ofs - block_ofs > 0) {
+    if (extent_ofs > block_ofs) {
       ldout(cct, 10) << "<1>zeroing " << buf_ofs << "~" << extent_ofs << dendl;
       r = cb(buf_ofs, extent_ofs - block_ofs, NULL, arg);
       if (r < 0) {
@@ -1404,7 +1404,7 @@ ssize_t handle_sparse_read(CephContext *cct,
   }
 
   /* last hole */
-  if (buf_len - buf_ofs) {
+  if (buf_len > buf_ofs) {
     ldout(cct, 10) << "<3>zeroing " << buf_ofs << "~" << buf_len - buf_ofs << dendl;
     r = cb(buf_ofs, buf_len - buf_ofs, NULL, arg);
     if (r < 0) {