Reread the CAB header skipping the self-extracting binary code.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15 as found
by the "OSS-Fuzz" project.

diff --git a/libarchive/archive_read_support_format_cab.c b/libarchive/archive_read_support_format_cab.c
index fc70684afa04feed1dbaef4eda7def7fb1cbf8d4..099f4a83dcacdeeba72146e03120ea770b008aad 100644 (file)
--- a/libarchive/archive_read_support_format_cab.c
+++ b/libarchive/archive_read_support_format_cab.c
@@ -645,12 +645,13 @@ cab_read_header(struct archive_read *a)
        cab = (struct cab *)(a->format->data);
        if (cab->found_header == 0 &&
            p[0] == 'M' && p[1] == 'Z') {
-               /* This is an executable?  Must be self-extracting...   */
+               /* This is an executable?  Must be self-extracting... */
                err = cab_skip_sfx(a);
                if (err < ARCHIVE_WARN)
                        return (err);
 
-               if ((p = __archive_read_ahead(a, sizeof(*p), NULL)) == NULL)
+               /* Re-read header after processing the SFX. */
+               if ((p = __archive_read_ahead(a, 42, NULL)) == NULL)
                        return (truncated_error(a));
        }