- djm@cvs.openbsd.org 2007/05/17 07:55:29

     [sftp-server.c]
     bz#1286 stop reading and processing commands when input or output buffer
     is nearly full, otherwise sftp-server would happily try to grow the
     input/output buffers past the maximum supported by the buffer API and
     promptly fatal()
     based on patch from Thue Janus Kristensen; feedback & ok dtucker@

diff --git a/ChangeLog b/ChangeLog
index 1f9a101f87a531521601b5e11881d4ede34a1be4..a735e05125b641ec5a80607cddb70b31bde8c36e 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,13 @@
    - djm@cvs.openbsd.org 2007/05/17 07:50:31
      [log.c]
      save and restore errno when logging; ok deraadt@
+   - djm@cvs.openbsd.org 2007/05/17 07:55:29
+     [sftp-server.c]
+     bz#1286 stop reading and processing commands when input or output buffer
+     is nearly full, otherwise sftp-server would happily try to grow the
+     input/output buffers past the maximum supported by the buffer API and
+     promptly fatal()
+     based on patch from Thue Janus Kristensen; feedback & ok dtucker@
 
 20070509
  - (tim) [configure.ac] Bug #1287: Add missing test for ucred.h.

diff --git a/sftp-server.c b/sftp-server.c
index d68584b52e6b97ceafcdf463ad3f9d5767998dad..76edebc5a6657ea78649a53754634d837ebd7c2b 100644 (file)
--- a/sftp-server.c
+++ b/sftp-server.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sftp-server.c,v 1.72 2007/04/18 01:12:43 stevesk Exp $ */
+/* $OpenBSD: sftp-server.c,v 1.73 2007/05/17 07:55:29 djm Exp $ */
 /*
  * Copyright (c) 2000-2004 Markus Friedl.  All rights reserved.
  *
@@ -1214,7 +1214,7 @@ main(int argc, char **argv)
        int in, out, max, ch, skipargs = 0, log_stderr = 0;
        ssize_t len, olen, set_size;
        SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
-       char *cp;
+       char *cp, buf[4*4096];
 
        extern char *optarg;
        extern char *__progname;
@@ -1298,7 +1298,15 @@ main(int argc, char **argv)
                memset(rset, 0, set_size);
                memset(wset, 0, set_size);
 
-               FD_SET(in, rset);
+               /*
+                * Ensure that we can read a full buffer and handle
+                * the worst-case length packet it can generate,
+                * otherwise apply backpressure by stopping reads.
+                */
+               if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
+                   buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
+                       FD_SET(in, rset);
+
                olen = buffer_len(&oqueue);
                if (olen > 0)
                        FD_SET(out, wset);
@@ -1312,7 +1320,6 @@ main(int argc, char **argv)
 
                /* copy stdin to iqueue */
                if (FD_ISSET(in, rset)) {
-                       char buf[4*4096];
                        len = read(in, buf, sizeof buf);
                        if (len == 0) {
                                debug("read eof");
@@ -1334,7 +1341,13 @@ main(int argc, char **argv)
                                buffer_consume(&oqueue, len);
                        }
                }
-               /* process requests from client */
-               process();
+
+               /*
+                * Process requests from client if we can fit the results
+                * into the output buffer, otherwise stop processing input
+                * and let the output queue drain.
+                */
+               if (buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
+                       process();
        }
 }