svn commit: r316431 - stable/11/sys/kern

[Gleb Smirnoff]

Author: glebius
Date: Mon Apr  3 00:46:32 2017
New Revision: 316431
URL: https://svnweb.freebsd.org/changeset/base/316431

Log:
  Merge r315910:
    Make sendfile(2) more robust against file change.  This fixes a possible
    crash when the file shrinks.  This also fixes sendfile(2) not sending more
    data in a case when the file grows, and the request is open-ended or
    specifies a size that is greater than old file size.
  
    PR:           217789
    Reviewed by:  gallatin

Modified:
  stable/11/sys/kern/kern_sendfile.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/kern/kern_sendfile.c
==============================================================================
--- stable/11/sys/kern/kern_sendfile.c	Sun Apr  2 21:30:05 2017	(r316430)
+++ stable/11/sys/kern/kern_sendfile.c	Mon Apr  3 00:46:32 2017	(r316431)
@@ -681,11 +681,10 @@ retry_space:
 				goto done;
 			}
 			if (va.va_size != obj_size) {
-				if (nbytes == 0)
-					rem += va.va_size - obj_size;
-				else if (offset + nbytes > va.va_size)
-					rem -= (offset + nbytes - va.va_size);
 				obj_size = va.va_size;
+				rem = nbytes ?
+				    omin(nbytes + offset, obj_size) : obj_size;
+				rem -= off;
 			}
 		}