tar: tighten up pax header validity check

function                                             old     new   delta
get_header_tar                                      1785    1795     +10

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index 32f842095..54d910431 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -115,7 +115,9 @@ static void process_pax_hdr(archive_handle_t *archive_handle, unsigned sz, int g
                  */
                 p += len;
                 sz -= len;
-                if ((int)sz < 0
+                if (
+                /** (int)sz < 0 - not good enough for huge malicious VALUE of 2^32-1 */
+                    (int)(sz|len) < 0 /* this works */
                  || len == 0
                  || errno != EINVAL
                  || *end != ' '