Reject non-regular sparse files

Thanks to Pavel Raiskup

diff --git a/libarchive/archive_read_support_format_tar.c b/libarchive/archive_read_support_format_tar.c
index eb60e1a0da04afd691f19ac78ba5c2ec484963c2..469666e8e5eb2d5a679c9a14b1baa4fc0e5b8d43 100644 (file)
--- a/libarchive/archive_read_support_format_tar.c
+++ b/libarchive/archive_read_support_format_tar.c
@@ -136,6 +136,7 @@ struct tar {
        int64_t                  entry_padding;
        int64_t                  entry_bytes_unconsumed;
        int64_t                  realsize;
+       int                      sparse_allowed;
        struct sparse_block     *sparse_list;
        struct sparse_block     *sparse_last;
        int64_t                  sparse_offset;
@@ -1271,6 +1272,14 @@ header_common(struct archive_read *a, struct tar *tar,
                 * sparse information in the extended area.
                 */
                /* FALLTHROUGH */
+       case '0':
+               /*
+                * Enable sparse file "read" support only for regular
+                * files and explicit GNU sparse files.  However, we
+                * don't allow non-standard file types to be sparse.
+                */
+               tar->sparse_allowed = 1;
+               /* FALLTHROUGH */
        default: /* Regular file  and non-standard types */
                /*
                 * Per POSIX: non-recognized types should always be
@@ -1728,6 +1737,14 @@ pax_attribute(struct archive_read *a, struct tar *tar,
                                 * NULL pointer to strlen().  */
        switch (key[0]) {
        case 'G':
+               /* Reject GNU.sparse.* headers on non-regular files. */
+               if (strncmp(key, "GNU.sparse", 10) == 0 &&
+                   !tar->sparse_allowed) {
+                       archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
+                           "Non-regular file cannot be sparse");
+                       return (ARCHIVE_FATAL);
+               }
+
                /* GNU "0.0" sparse pax format. */
                if (strcmp(key, "GNU.sparse.numblocks") == 0) {
                        tar->sparse_offset = -1;