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9pfs: check the size of transport buffer before marshaling 

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 8d37de41ca # 2.10]
Signed-off-by: Greg Kurz <groug@kaod.org>
This commit is contained in:
Jan Dakinevich 2017-09-20 08:48:52 +02:00 committed by Greg Kurz
parent 4d8bc7334b
commit 772a73692e
1 changed files with 14 additions and 5 deletions
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19
hw/9pfs/9p.c
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@ -1748,18 +1748,27 @@ static int coroutine_fn v9fs_do_readdir_with_stat(V9fsPDU *pdu,
if (err < 0) {
break;
}
/* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */
len = pdu_marshal(pdu, 11 + count, "S", &v9stat);
if ((count + v9stat.size + 2) > max_count) {
v9fs_readdir_unlock(&fidp->fs.dir);
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 */
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 < 0) {
v9fs_co_seekdir(pdu, fidp, saved_dir_pos);
v9fs_stat_free(&v9stat);
v9fs_path_free(&path);
return len;
}
count += len;
v9fs_stat_free(&v9stat);
v9fs_path_free(&path);