>
> When lookup_tree() or lookup_blob() cannot find a tree entry's object,
> 'o' is set to NULL via:
>
>     o = child ? &child->object : NULL;
>
> The subsequent null-check catches this correctly, but then dereferences
> 'o' to format the error message:
>
>     error(_("failed to find object %s"), oid_to_hex(&o->oid));
>
> This causes a segfault instead of the intended diagnostic output.
>
> Fix this by using &entry.oid instead. 'entry' is the struct name_entry
> populated by tree_entry() on each loop iteration and holds the OID of
> the failing lookup -- which is exactly what the error should report.
>
> This crash is reachable via git-backfill(1) when a tree entry's object
> is absent from the local object database.
>
> Signed-off-by: Yuvraj Singh Chauhan <ysinghcin@gmail.com>
> ---
>  path-walk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/path-walk.c b/path-walk.c
> index 364e4cfa19..839582380c 100644
> --- a/path-walk.c
> +++ b/path-walk.c
> @@ -171,7 +171,7 @@ static int add_tree_entries(struct path_walk_context *ctx,
>
>                 if (!o) {
>                         error(_("failed to find object %s"),
> -                             oid_to_hex(&o->oid));
> +                             oid_to_hex(&entry.oid));
>                         return -1;
>                 }
>
> --
> 2.53.0.582.gca1db8a0f7