zero-uio-on-zero-read-20071127

LICENSE IPL10

avoid leaking random data in a read of a 0 length object.

diff --git a/src/afs/VNOPS/afs_vnop_read.c b/src/afs/VNOPS/afs_vnop_read.c
index 9a104e1..8089e68 100644 (file)
--- a/src/afs/VNOPS/afs_vnop_read.c
+++ b/src/afs/VNOPS/afs_vnop_read.c
@@ -117,7 +117,21 @@ afs_MemRead(register struct vcache *avc, struct uio *auio,
      * Locks held:
      * avc->lock(R)
      */
-    while (totalLength > 0) {
+    if (filePos >= avc->m.Length) {
+       if (len > AFS_ZEROS)
+           len = sizeof(afs_zeros);    /* and in 0 buffer */
+#ifdef AFS_DARWIN80_ENV
+       trimlen = len;
+       tuiop = afsio_darwin_partialcopy(auio, trimlen);
+#else
+       afsio_copy(auio, &tuio, tvec);
+       trimlen = len;
+       afsio_trim(&tuio, trimlen);
+#endif
+       AFS_UIOMOVE(afs_zeros, trimlen, UIO_READ, tuiop, code);
+    }
+
+    while (avc->m.Length > 0 && totalLength > 0) {
        /* read all of the cached info */
        if (filePos >= avc->m.Length)
            break;              /* all done */
@@ -536,7 +550,22 @@ afs_UFSRead(register struct vcache *avc, struct uio *auio,
     }
 #endif
 
-    while (totalLength > 0) {
+    if (filePos >= avc->m.Length) {
+       if (len > AFS_ZEROS)
+           len = sizeof(afs_zeros);    /* and in 0 buffer */
+       len = 0;
+#ifdef AFS_DARWIN80_ENV
+       trimlen = len;
+       tuiop = afsio_darwin_partialcopy(auio, trimlen);
+#else
+       afsio_copy(auio, &tuio, tvec);
+       trimlen = len;
+       afsio_trim(&tuio, trimlen);
+#endif
+       AFS_UIOMOVE(afs_zeros, trimlen, UIO_READ, tuiop, code);
+    }
+
+    while (avc->m.Length > 0 && totalLength > 0) {
        /* read all of the cached info */
        if (filePos >= avc->m.Length)
            break;              /* all done */