Issue 547: problems with compress bidder

The code previously was not very careful about verifying the
compression parameters.  This led to cases where it failed to
reject invalid compressed data at the beginning.  The invalid
left shift was one symptom of this.

The code is now more careful:  It verifies that the compression
parameter byte exists and verifies that the maximum code size
is <= 16 bits.

This also includes some new tests to verify that truncated or
otherwise invalid compressed data is rejected.

diff --git a/libarchive/archive_read_support_filter_compress.c b/libarchive/archive_read_support_filter_compress.c
index 832771f8dc74cf8bac71c99bc0ba2cf3052c8d5c..e05132dbfaec2cb0271a6d28a586142fe170c260 100644 (file)
--- a/libarchive/archive_read_support_filter_compress.c
+++ b/libarchive/archive_read_support_filter_compress.c
@@ -185,19 +185,22 @@ compress_bidder_bid(struct archive_read_filter_bidder *self,
 
        (void)self; /* UNUSED */
 
-       buffer = __archive_read_filter_ahead(filter, 2, &avail);
+       /* Shortest valid compress file is 3 bytes. */
+       buffer = __archive_read_filter_ahead(filter, 3, &avail);
 
        if (buffer == NULL)
                return (0);
 
        bits_checked = 0;
+       /* First two bytes are the magic value */
        if (buffer[0] != 0x1F || buffer[1] != 0x9D)
                return (0);
-       bits_checked += 16;
-
-       /*
-        * TODO: Verify more.
-        */
+       /* Third byte holds compression parameters. */
+       if (buffer[2] & 0x20) /* Reserved bit, must be zero. */
+               return (0);
+       if (buffer[2] & 0x40) /* Reserved bit, must be zero. */
+               return (0);
+       bits_checked += 18;
 
        return (bits_checked);
 }
@@ -239,7 +242,13 @@ compress_bidder_init(struct archive_read_filter *self)
        (void)getbits(self, 8); /* Skip first signature byte. */
        (void)getbits(self, 8); /* Skip second signature byte. */
 
+       /* Get compression parameters. */
        code = getbits(self, 8);
+       if ((code & 0x1f) > 16) {
+               archive_set_error(&self->archive->archive, -1,
+                   "Invalid compressed data");
+               return (ARCHIVE_FATAL);
+       }
        state->maxcode_bits = code & 0x1f;
        state->maxcode = (1 << state->maxcode_bits);
        state->use_reset_code = code & 0x80;

diff --git a/libarchive/test/test_read_filter_compress.c b/libarchive/test/test_read_filter_compress.c
new file mode 100644 (file)
index 0000000..03a1d5f
--- /dev/null
+++ b/libarchive/test/test_read_filter_compress.c
@@ -0,0 +1,80 @@
+/*-
+ * Copyright (c) 2003-2008 Tim Kientzle
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "test.h"
+
+DEFINE_TEST(test_read_filter_compress_truncated)
+{
+       const char data[] = {0x1f, 0x9d};
+       struct archive *a;
+
+       assert((a = archive_read_new()) != NULL);
+       assertEqualIntA(a, ARCHIVE_OK, archive_read_support_filter_compress(a));
+       assertEqualIntA(a, ARCHIVE_OK, archive_read_support_format_all(a));
+       assertEqualIntA(a, ARCHIVE_FATAL,
+           archive_read_open_memory(a, data, sizeof(data)));
+
+       assertEqualInt(ARCHIVE_OK, archive_read_close(a));
+       assertEqualInt(ARCHIVE_OK, archive_read_free(a));
+}
+
+
+DEFINE_TEST(test_read_filter_compress_empty2)
+{
+       const char data[] = {0x1f, 0x9d, 0x10};
+       struct archive *a;
+       struct archive_entry *ae;
+
+       assert((a = archive_read_new()) != NULL);
+       assertEqualIntA(a, ARCHIVE_OK, archive_read_support_filter_compress(a));
+       assertEqualIntA(a, ARCHIVE_OK, archive_read_support_format_all(a));
+       assertEqualIntA(a, ARCHIVE_OK,
+           archive_read_open_memory(a, data, sizeof(data)));
+
+       assertEqualIntA(a, ARCHIVE_EOF, archive_read_next_header(a, &ae));
+
+       /* Verify that the format detection worked. */
+       assertEqualInt(archive_filter_code(a, 0), ARCHIVE_FILTER_COMPRESS);
+       assertEqualString(archive_filter_name(a, 0), "compress (.Z)");
+       assertEqualInt(archive_format(a), ARCHIVE_FORMAT_EMPTY);
+
+       assertEqualInt(ARCHIVE_OK, archive_read_close(a));
+       assertEqualInt(ARCHIVE_OK, archive_read_free(a));
+}
+
+
+DEFINE_TEST(test_read_filter_compress_invalid)
+{
+       const char data[] = {0x1f, 0x9d, 0x11};
+       struct archive *a;
+
+       assert((a = archive_read_new()) != NULL);
+       assertEqualIntA(a, ARCHIVE_OK, archive_read_support_filter_compress(a));
+       assertEqualIntA(a, ARCHIVE_OK, archive_read_support_format_all(a));
+       assertEqualIntA(a, ARCHIVE_FATAL,
+           archive_read_open_memory(a, data, sizeof(data)));
+
+       assertEqualInt(ARCHIVE_OK, archive_read_close(a));
+       assertEqualInt(ARCHIVE_OK, archive_read_free(a));
+}