From: Adam Stylinski <kungfujesus06@gmail.com>
Date: Wed, 27 Apr 2022 01:53:30 +0000 (-0400)
Subject: Fixed regression introduced by inlining CRC + copy
X-Git-Tag: 2.1.0-beta1~260
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84f116a3d782b39047b666bc6804e2c0c2138e6d;p=thirdparty%2Fzlib-ng.git

Fixed regression introduced by inlining CRC + copy

Pretty much every time updatewindow has been called, implicitly a
checksum was performed unless on s/390 or state->wrap & 4 == 0. The
inflateSetDictionary function instead separately calls this checksum
before invoking update window and checks the checksum to see if it
matches the initial checksum (a property that happens from parsing the
DICTID section of the headers).

Instead, we can make updatewindow have a "copy" parameter, which is the
state->wrap value that is being checked anyway.  We instead move the 3rd
bit check to be checked by the caller rather than the callee.
---

diff --git a/inflate.c b/inflate.c
index 8ada6466a..8a48e7933 100644
--- a/inflate.c
+++ b/inflate.c
@@ -15,7 +15,7 @@
 
 /* function prototypes */
 static int inflateStateCheck(PREFIX3(stream) *strm);
-static int updatewindow(PREFIX3(stream) *strm, const uint8_t *end, uint32_t copy);
+static int updatewindow(PREFIX3(stream) *strm, const uint8_t *end, uint32_t len, int32_t cksum);
 static uint32_t syncsearch(uint32_t *have, const unsigned char *buf, uint32_t len);
 
 static inline void inf_chksum_cpy(PREFIX3(stream) *strm, uint8_t *dst,
@@ -237,7 +237,7 @@ int Z_INTERNAL PREFIX(inflate_ensure_window)(struct inflate_state *state) {
    output will fall in the output data, making match copies simpler and faster.
    The advantage may be dependent on the size of the processor's data caches.
  */
-static int32_t updatewindow(PREFIX3(stream) *strm, const uint8_t *end, uint32_t copy) {
+static int32_t updatewindow(PREFIX3(stream) *strm, const uint8_t *end, uint32_t len, int32_t cksum) {
     struct inflate_state *state;
     uint32_t dist;
 
@@ -245,16 +245,16 @@ static int32_t updatewindow(PREFIX3(stream) *strm, const uint8_t *end, uint32_t
 
     if (PREFIX(inflate_ensure_window)(state)) return 1;
 
-    /* copy state->wsize or less output bytes into the circular window */
-    if (copy >= state->wsize) {
+    /* len state->wsize or less output bytes into the circular window */
+    if (len >= state->wsize) {
         /* Only do this if the caller specifies to checksum bytes AND the platform requires
          * it (s/390 being the primary exception to this. Also, for now, do the adler checksums
          * if not a gzip based header. The inline adler checksums will come in the near future,
          * possibly the next commit */
-        if (INFLATE_NEED_CHECKSUM(strm) && (state->wrap & 4)) {
+        if (INFLATE_NEED_CHECKSUM(strm) && cksum) {
             /* We have to split the checksum over non-copied and copied bytes */
-            if (copy > state->wsize)
-                inf_chksum(strm, end - copy, copy - state->wsize);
+            if (len > state->wsize)
+                inf_chksum(strm, end - len, len - state->wsize);
             inf_chksum_cpy(strm, state->window, end - state->wsize, state->wsize);
         } else {
             memcpy(state->window, end - state->wsize, state->wsize);
@@ -266,21 +266,21 @@ static int32_t updatewindow(PREFIX3(stream) *strm, const uint8_t *end, uint32_t
         dist = state->wsize - state->wnext;
         /* Only do this if the caller specifies to checksum bytes AND the platform requires
          * We need to maintain the correct order here for the checksum */
-        dist = MIN(dist, copy);
-        if (INFLATE_NEED_CHECKSUM(strm) && (state->wrap & 4)) {
-            inf_chksum_cpy(strm, state->window + state->wnext, end - copy, dist);
+        dist = MIN(dist, len);
+        if (INFLATE_NEED_CHECKSUM(strm) && cksum) {
+            inf_chksum_cpy(strm, state->window + state->wnext, end - len, dist);
         } else {
-            memcpy(state->window + state->wnext, end - copy, dist);
+            memcpy(state->window + state->wnext, end - len, dist);
         }
-        copy -= dist;
-        if (copy) {
-            if (INFLATE_NEED_CHECKSUM(strm) && (state->wrap & 4)) {
-                inf_chksum_cpy(strm, state->window, end - copy, copy);
+        len -= dist;
+        if (len) {
+            if (INFLATE_NEED_CHECKSUM(strm) && cksum) {
+                inf_chksum_cpy(strm, state->window, end - len, len);
             } else {
-                memcpy(state->window, end - copy, copy);
+                memcpy(state->window, end - len, len);
             }
 
-            state->wnext = copy;
+            state->wnext = len;
             state->whave = state->wsize;
         } else {
             state->wnext += dist;
@@ -1070,7 +1070,8 @@ int32_t Z_EXPORT PREFIX(inflate)(PREFIX3(stream) *strm, int32_t flush) {
     if (INFLATE_NEED_UPDATEWINDOW(strm) &&
             (state->wsize || (out != strm->avail_out && state->mode < BAD &&
                  (state->mode < CHECK || flush != Z_FINISH)))) {
-        if (updatewindow(strm, strm->next_out, out - strm->avail_out)) {
+        /* update sliding window with respective checksum if not in "raw" mode */
+        if (updatewindow(strm, strm->next_out, out - strm->avail_out, state->wrap & 4)) {
             state->mode = MEM;
             return Z_MEM_ERROR;
         }
@@ -1140,7 +1141,7 @@ int32_t Z_EXPORT PREFIX(inflateSetDictionary)(PREFIX3(stream) *strm, const uint8
 
     /* copy dictionary to window using updatewindow(), which will amend the
        existing dictionary if appropriate */
-    ret = updatewindow(strm, dictionary + dictLength, dictLength);
+    ret = updatewindow(strm, dictionary + dictLength, dictLength, 0);
     if (ret) {
         state->mode = MEM;
         return Z_MEM_ERROR;