Correct incorrect inputs provided to the CRC functions.

The previous releases of zlib were not sensitive to incorrect CRC inputs with bits set above the low 32. This commit restores that behavior, so that applications with such bugs will continue to operate as before.
SkyN9ne · Mar 30, 2022 · ec3df00 · ec3df00
1 parent ce12773
commit ec3df00
Showing 1 changed file with 4 additions and 4 deletions.
diff --git a/crc32.c b/crc32.c
@@ -630,7 +630,7 @@ unsigned long ZEXPORT crc32_z(crc, buf, len)
 #endif /* DYNAMIC_CRC_TABLE */
 
     /* Pre-condition the CRC */
-    crc ^= 0xffffffff;
+    crc = (~crc) & 0xffffffff;
 
     /* Compute the CRC up to a word boundary. */
     while (len && ((z_size_t)buf & 7) != 0) {
@@ -749,7 +749,7 @@ unsigned long ZEXPORT crc32_z(crc, buf, len)
 #endif /* DYNAMIC_CRC_TABLE */
 
     /* Pre-condition the CRC */
-    crc ^= 0xffffffff;
+    crc = (~crc) & 0xffffffff;
 
 #ifdef W
 
@@ -1077,7 +1077,7 @@ uLong ZEXPORT crc32_combine64(crc1, crc2, len2)
 #ifdef DYNAMIC_CRC_TABLE
     once(&made, make_crc_table);
 #endif /* DYNAMIC_CRC_TABLE */
-    return multmodp(x2nmodp(len2, 3), crc1) ^ crc2;
+    return multmodp(x2nmodp(len2, 3), crc1) ^ (crc2 & 0xffffffff);
 }
 
 /* ========================================================================= */
@@ -1112,5 +1112,5 @@ uLong crc32_combine_op(crc1, crc2, op)
     uLong crc2;
     uLong op;
 {
-    return multmodp(op, crc1) ^ crc2;
+    return multmodp(op, crc1) ^ (crc2 & 0xffffffff);
 }