fix dereferencing null pointer in file_new()

file_new() sets file to NULL first.
when file_new() fails, file is set to NULL if it doesn't need to be freed
so, only free when need to. otherwise would deference a null pointer.

Found this from clang's analyzer
Fixes #1140

diff --git a/libarchive/archive_write_set_format_7zip.c b/libarchive/archive_write_set_format_7zip.c
index f63a2266a85ede17a747a7c7796992fcf431c937..92a87f74e62507c0d5604a9a2b9060a4d713a1d4 100644 (file)
--- a/libarchive/archive_write_set_format_7zip.c
+++ b/libarchive/archive_write_set_format_7zip.c
@@ -439,7 +439,8 @@ _7z_write_header(struct archive_write *a, struct archive_entry *entry)
 
        r = file_new(a, entry, &file);
        if (r < ARCHIVE_WARN) {
-               file_free(file);
+               if (file != NULL)
+                       file_free(file);
                return (r);
        }
        if (file->size == 0 && file->dir) {