From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 15 Feb 2010 14:51:28 +0000 (-0500)
Subject: libext2fs: Fix byte swapping bugs
X-Git-Tag: v1.42-WIP-0702~113
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d18a55c528adf997d8edee60bd8003c822c55e8;p=thirdparty%2Fe2fsprogs.git

libext2fs: Fix byte swapping bugs

The 64-bit patches broke compiles on big endian systems.  In addition
the block group checksum test was failing, due to bugs in both the
test case and the checksum code itself.  This commit addresses these
problems.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c
index 4781c3482..b9a1e4486 100644
--- a/lib/ext2fs/closefs.c
+++ b/lib/ext2fs/closefs.c
@@ -270,7 +270,7 @@ errcode_t ext2fs_flush(ext2_filsys fs)
 	struct ext2_super_block *super_shadow = 0;
 	struct ext2_group_desc *group_shadow = 0;
 #ifdef WORDS_BIGENDIAN
-	ext2_group_desc *gdp;
+	struct ext2_group_desc *gdp;
 	dgrp_t		j;
 #endif
 	char	*group_ptr;
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 60bdc117b..b301749df 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -33,6 +33,15 @@ STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 {
 	__u16 crc = 0;
 	struct ext2_group_desc *desc;
+	size_t size;
+
+	size = fs->super->s_desc_size;
+	if (size < EXT2_MIN_DESC_SIZE)
+		size = EXT2_MIN_DESC_SIZE;
+	if (size > sizeof(struct ext4_group_desc)) {
+		printf("%s: illegal s_desc_size(%zd)\n", __func__, size);
+		size = sizeof(struct ext4_group_desc);
+	}
 
 	desc = ext2fs_group_desc(fs, fs->group_desc, group);
 
@@ -40,11 +49,13 @@ STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 		int offset = offsetof(struct ext2_group_desc, bg_checksum);
 
 #ifdef WORDS_BIGENDIAN
-		struct ext2_group_desc swabdesc = *desc;
+		struct ext4_group_desc swabdesc;
 
 		/* Have to swab back to little-endian to do the checksum */
-		ext2fs_swap_group_desc2(fs, &swabdesc);
-		desc = &swabdesc;
+		memcpy(&swabdesc, desc, size);
+		ext2fs_swap_group_desc2(fs,
+					(struct ext2_group_desc *) &swabdesc);
+		desc = (struct ext2_group_desc *) &swabdesc;
 
 		group = ext2fs_swab32(group);
 #endif
@@ -54,9 +65,9 @@ STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 		crc = ext2fs_crc16(crc, desc, offset);
 		offset += sizeof(desc->bg_checksum); /* skip checksum */
 		/* for checksum of struct ext4_group_desc do the rest...*/
-		if (offset < fs->super->s_desc_size) {
+		if (offset < size) {
 			crc = ext2fs_crc16(crc, (char *)desc + offset,
-				    fs->super->s_desc_size - offset);
+					   size - offset);
 		}
 	}
 
@@ -153,14 +164,23 @@ void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
 	__u16 crc1, crc2, crc3;
 	dgrp_t swabgroup;
  	struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc, group);
+	size_t size;
 	struct ext2_super_block *sb = fs->super;
-
+	int offset = offsetof(struct ext2_group_desc, bg_checksum);
 #ifdef WORDS_BIGENDIAN
-	struct ext2_group_desc swabdesc = fs->group_desc[group];
+	struct ext4_group_desc swabdesc;
+#endif
 
+	size = fs->super->s_desc_size;
+	if (size < EXT2_MIN_DESC_SIZE)
+		size = EXT2_MIN_DESC_SIZE;
+	if (size > sizeof(struct ext4_group_desc))
+		size = sizeof(struct ext4_group_desc);
+#ifdef WORDS_BIGENDIAN
 	/* Have to swab back to little-endian to do the checksum */
-	ext2fs_swap_group_desc2(fs, fs->group_desc, &swabdesc);
-	desc = &swabdesc;
+	memcpy(&swabdesc, desc, size);
+	ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
+	desc = (struct ext2_group_desc *) &swabdesc;
 
 	swabgroup = ext2fs_swab32(group);
 #else
@@ -169,8 +189,12 @@ void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
 
 	crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
 	crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
-	crc3 = ext2fs_crc16(crc2, desc,
-			    offsetof(struct ext2_group_desc, bg_checksum));
+	crc3 = ext2fs_crc16(crc2, desc, offset);
+	offset += sizeof(desc->bg_checksum); /* skip checksum */
+	/* for checksum of struct ext4_group_desc do the rest...*/
+	if (offset < size)
+		crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
+
 	printf("%s: UUID %016Lx%016Lx(%04x), grp %u(%04x): %04x=%04x\n",
 	       msg, *(long long *)&sb->s_uuid, *(long long *)&sb->s_uuid[8],
 	       crc1, group, crc2, crc3, ext2fs_group_desc_csum(fs, group));