Commit abb0cc02fb for qemu.org

commit abb0cc02fb56e2432837e34b80fe68768f95e774
Author: Christian Schoenebeck <qemu_oss@crudebyte.com>
Date:   Mon May 18 19:35:36 2026 +0200

    hw/9pfs: add NULL check in v9fs_path_is_ancestor()

    Add NULL check for s1->data and s2->data before using them in
    string operations. This prevents potential crashes when dealing
    with uninitialized paths.

    This is just a defensive measure. We are currently never passing
    NULL to this function.

    Link: https://lore.kernel.org/qemu-devel/3348c4d683f061c23083bd45994d527be4fb7cbc.1779126034.git.qemu_oss@crudebyte.com
    Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index e2713b9eee..e590c414ab 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -241,6 +241,9 @@ int v9fs_name_to_path(V9fsState *s, V9fsPath *dirpath,
  */
 static int v9fs_path_is_ancestor(V9fsPath *s1, V9fsPath *s2)
 {
+    if (!s1->data || !s2->data) {
+        return 0;
+    }
     if (!strncmp(s1->data, s2->data, s1->size - 1)) {
         if (s2->data[s1->size - 1] == '\0' || s2->data[s1->size - 1] == '/') {
             return 1;