[Qemu-devel] [PATCH] 9pfs: fix potential segfault during walk

[Greg Kurz]

If the call to fid_to_qid() returns an error, we will call v9fs_path_free()
on uninitialized paths.

Let's fix this by initializing dpath and path before calling fid_to_qid().

Signed-off-by: Greg Kurz <address@hidden>
---

Thanks Paolo (and Coverity) for spotting this.

Cc'ing stable as this is a regression introduced in 2.7. It is also present
in Michael's stable-2.6-staging branch.

 hw/9pfs/9p.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index dfe293d11d1c..91a497079acb 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1320,13 +1320,14 @@ static void v9fs_walk(void *opaque)
         goto out_nofid;
     }
 
+    v9fs_path_init(&dpath);
+    v9fs_path_init(&path);
+
     err = fid_to_qid(pdu, fidp, &qid);
     if (err < 0) {
         goto out;
     }
 
-    v9fs_path_init(&dpath);
-    v9fs_path_init(&path);
     /*
      * Both dpath and path initially poin to fidp.
      * Needed to handle request with nwnames == 0