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[PULL,3/3] 9pfs: check the size of transport buffer before marshaling

Message ID 20170920135038.21058-4-groug@kaod.org
State New
Headers show
Series [PULL,1/3] 9pfs: fix readdir() for 9p2000.u | expand

Commit Message

Greg Kurz Sept. 20, 2017, 1:50 p.m. UTC 
From: Jan Dakinevich <jan.dakinevich@gmail.com>

v9fs_do_readdir_with_stat() should check for a maximum buffer size
before an attempt to marshal gathered data. Otherwise, buffers assumed
as misconfigured and the transport would be broken.

The patch brings v9fs_do_readdir_with_stat() in conformity with
v9fs_do_readdir() behavior.

Signed-off-by: Jan Dakinevich <jan.dakinevich@gmail.com>
[groug, regression caused my commit 8d37de41cab1 # 2.10]
Signed-off-by: Greg Kurz <groug@kaod.org>
---
 hw/9pfs/9p.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)
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Patch

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index cdd44bdc82ef..23ac7bb532f0 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1748,17 +1748,26 @@  static int coroutine_fn v9fs_do_readdir_with_stat(V9fsPDU *pdu,
         if (err < 0) {
             break;
         }
+        if ((count + v9stat.size + 2) > max_count) {
+            v9fs_readdir_unlock(&fidp->fs.dir);
+
+            /* Ran out of buffer. Set dir back to old position and return */
+            v9fs_co_seekdir(pdu, fidp, saved_dir_pos);
+            v9fs_stat_free(&v9stat);
+            v9fs_path_free(&path);
+            return count;
+        }
+
         /* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */
         len = pdu_marshal(pdu, 11 + count, "S", &v9stat);
 
         v9fs_readdir_unlock(&fidp->fs.dir);
 
-        if ((len != (v9stat.size + 2)) || ((count + len) > max_count)) {
-            /* Ran out of buffer. Set dir back to old position and return */
+        if (len < 0) {
             v9fs_co_seekdir(pdu, fidp, saved_dir_pos);
             v9fs_stat_free(&v9stat);
             v9fs_path_free(&path);
-            return count;
+            return len;
         }
         count += len;
         v9fs_stat_free(&v9stat);