[gnome-remote-desktop] rdp-fuse-clipboard: Fix potential race when accessing FuseFile path

[Jonas Ådahl <jadahl src gnome org>]

commit 17fc830ef38765c627530eec1e2a8f0523a57d7a
Author: Pascal Nowack <Pascal Nowack gmx de>
Date:   Mon Oct 18 09:23:31 2021 +0200

    rdp-fuse-clipboard: Fix potential race when accessing FuseFile path
    
    When outputting debug information about which FuseFile is opened, the
    FuseFile path might already be invalid, since the FuseFile could
    already be deleted due to a new clipboard selection.
    While this situation is unlikely to happen, since pasting content and
    copying content would have to happen at the same time, it is in theory
    still possible.
    
    So, duplicate the FuseFile path before unlocking the filesystem mutex.
    This will avoid this situation.

 src/grd-rdp-fuse-clipboard.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
---
diff --git a/src/grd-rdp-fuse-clipboard.c b/src/grd-rdp-fuse-clipboard.c
index fb1c66c..9acc9d4 100644
--- a/src/grd-rdp-fuse-clipboard.c
+++ b/src/grd-rdp-fuse-clipboard.c
@@ -1083,6 +1083,7 @@ fuse_ll_open (fuse_req_t             fuse_req,
 {
   GrdRdpFuseClipboard *rdp_fuse_clipboard = fuse_req_userdata (fuse_req);
   FuseFile *fuse_file;
+  g_autofree char *filename_with_root = NULL;
 
   g_mutex_lock (&rdp_fuse_clipboard->filesystem_mutex);
   if (!(fuse_file = get_fuse_file_by_ino (rdp_fuse_clipboard, fuse_ino)))
@@ -1097,6 +1098,8 @@ fuse_ll_open (fuse_req_t             fuse_req,
       fuse_reply_err (fuse_req, EISDIR);
       return;
     }
+
+  filename_with_root = g_strdup (fuse_file->filename_with_root);
   g_mutex_unlock (&rdp_fuse_clipboard->filesystem_mutex);
 
   if ((file_info->flags & O_ACCMODE) != O_RDONLY)
@@ -1108,7 +1111,7 @@ fuse_ll_open (fuse_req_t             fuse_req,
   /* Using direct_io also increases FUSE_MAX_PAGES_PER_REQ */
   file_info->direct_io = 1;
 
-  g_debug ("[FUSE Clipboard] Opening file \"%s\"", fuse_file->filename_with_root);
+  g_debug ("[FUSE Clipboard] Opening file \"%s\"", filename_with_root);
   fuse_reply_open (fuse_req, file_info);
 }
 
@@ -1157,6 +1160,7 @@ fuse_ll_opendir (fuse_req_t             fuse_req,
 {
   GrdRdpFuseClipboard *rdp_fuse_clipboard = fuse_req_userdata (fuse_req);
   FuseFile *fuse_file;
+  g_autofree char *filename_with_root = NULL;
 
   g_mutex_lock (&rdp_fuse_clipboard->filesystem_mutex);
   if (!(fuse_file = get_fuse_file_by_ino (rdp_fuse_clipboard, fuse_ino)))
@@ -1171,6 +1175,8 @@ fuse_ll_opendir (fuse_req_t             fuse_req,
       fuse_reply_err (fuse_req, ENOTDIR);
       return;
     }
+
+  filename_with_root = g_strdup (fuse_file->filename_with_root);
   g_mutex_unlock (&rdp_fuse_clipboard->filesystem_mutex);
 
   if ((file_info->flags & O_ACCMODE) != O_RDONLY)
@@ -1179,8 +1185,7 @@ fuse_ll_opendir (fuse_req_t             fuse_req,
       return;
     }
 
-  g_debug ("[FUSE Clipboard] Opening directory \"%s\"",
-           fuse_file->filename_with_root);
+  g_debug ("[FUSE Clipboard] Opening directory \"%s\"", filename_with_root);
   fuse_reply_open (fuse_req, file_info);
 }