{lzx,xpress}_decode_match(): Fix undefined pointer evalution

[wimlib] / src / lzx-decompress.c

diff --git a/src/lzx-decompress.c b/src/lzx-decompress.c
index a24b0832e14be6b955499a621b0da710347cb833..96332dd8f40cf6066ed43d19c482d38c7c6e5408 100644 (file)
--- a/src/lzx-decompress.c
+++ b/src/lzx-decompress.c
@@ -656,8 +656,6 @@ lzx_decode_match(unsigned main_element, int block_type,
        /* Verify that the match is in the bounds of the part of the window
         * currently in use, then copy the source of the match to the current
         * position. */
-       match_dest = window + window_pos;
-       match_src = match_dest - match_offset;
 
        if (match_len > bytes_remaining) {
                DEBUG("lzx_decode_match(): Match of length %u bytes overflows "
@@ -665,13 +663,16 @@ lzx_decode_match(unsigned main_element, int block_type,
                return -1;
        }
 
-       if (match_src < window) {
+       if (match_offset > window_pos) {
                DEBUG("lzx_decode_match(): Match of length %u bytes references "
                      "data before window (match_offset = %u, window_pos = %u)",
                      match_len, match_offset, window_pos);
                return -1;
        }
 
+       match_dest = window + window_pos;
+       match_src = match_dest - match_offset;
+
 #if 0
        printf("Match: src %u, dst %u, len %u\n", match_src - window,
                                                match_dest - window,