From: Tim Kientzle <kientzle@acm.org>
Date: Sun, 11 Sep 2016 21:20:31 +0000 (-0700)
Subject: Reject non-regular sparse files
X-Git-Tag: v3.2.2~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=56fc1f1e005c96126a6b63053ca4c9fad0705cf4;p=thirdparty%2Flibarchive.git

Reject non-regular sparse files

Thanks to Pavel Raiskup
---

diff --git a/libarchive/archive_read_support_format_tar.c b/libarchive/archive_read_support_format_tar.c
index eb60e1a0d..469666e8e 100644
--- a/libarchive/archive_read_support_format_tar.c
+++ b/libarchive/archive_read_support_format_tar.c
@@ -136,6 +136,7 @@ struct tar {
 	int64_t			 entry_padding;
 	int64_t 		 entry_bytes_unconsumed;
 	int64_t			 realsize;
+	int			 sparse_allowed;
 	struct sparse_block	*sparse_list;
 	struct sparse_block	*sparse_last;
 	int64_t			 sparse_offset;
@@ -1271,6 +1272,14 @@ header_common(struct archive_read *a, struct tar *tar,
 		 * sparse information in the extended area.
 		 */
 		/* FALLTHROUGH */
+	case '0':
+		/*
+		 * Enable sparse file "read" support only for regular
+		 * files and explicit GNU sparse files.  However, we
+		 * don't allow non-standard file types to be sparse.
+		 */
+		tar->sparse_allowed = 1;
+		/* FALLTHROUGH */
 	default: /* Regular file  and non-standard types */
 		/*
 		 * Per POSIX: non-recognized types should always be
@@ -1728,6 +1737,14 @@ pax_attribute(struct archive_read *a, struct tar *tar,
 				 * NULL pointer to strlen().  */
 	switch (key[0]) {
 	case 'G':
+		/* Reject GNU.sparse.* headers on non-regular files. */
+		if (strncmp(key, "GNU.sparse", 10) == 0 &&
+		    !tar->sparse_allowed) {
+			archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
+			    "Non-regular file cannot be sparse");
+			return (ARCHIVE_FATAL);
+		}
+
 		/* GNU "0.0" sparse pax format. */
 		if (strcmp(key, "GNU.sparse.numblocks") == 0) {
 			tar->sparse_offset = -1;