gunzip: inflate_codes(): add fix from upstream gzip to prevent false CRC error

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/archival/libunarchive/decompress_unzip.c b/archival/libunarchive/decompress_unzip.c
index feaa047bd..33e877ec8 100644
--- a/archival/libunarchive/decompress_unzip.c
+++ b/archival/libunarchive/decompress_unzip.c
@@ -575,13 +575,16 @@ static NOINLINE int inflate_codes(STATE_PARAM_ONLY)
                         do {
                                 /* Was: nn -= (e = (e = GUNZIP_WSIZE - ((dd &= GUNZIP_WSIZE - 1) > w ? dd : w)) > nn ? nn : e); */
                                 /* Who wrote THAT?? rewritten as: */
+                                unsigned delta;
+
                                 dd &= GUNZIP_WSIZE - 1;
                                 e = GUNZIP_WSIZE - (dd > w ? dd : w);
+                                delta = w > dd ? w - dd : dd - w;
                                 if (e > nn) e = nn;
                                 nn -= e;
 
                                 /* copy to new buffer to prevent possible overwrite */
-                                if (w - dd >= e) {      /* (this test assumes unsigned comparison) */
+                                if (delta >= e) {
                                         memcpy(gunzip_window + w, gunzip_window + dd, e);
                                         w += e;
                                         dd += e;