[PATCH] Fix 32-bit overflow problems: dgrp_t * s_blocks_per_group

[Theodore Ts'o <tytso@mit.edu>]

There are a number of places where we multiply a dgrp_t with
s_blocks_per_group expecting that we will get a blk64_t.  This
requires a cast, or using the convenience function
ext2fs_group_first_block2().

This audit was suggested by Eric Sandeen.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 e2fsck/super.c         |  6 +++---
 lib/ext2fs/alloc.c     |  6 ++----
 lib/ext2fs/extent.c    |  3 +--
 lib/ext2fs/mkjournal.c |  4 +---
 resize/resize2fs.c     | 10 ++++------
 5 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/e2fsck/super.c b/e2fsck/super.c
index 160991d..b4b5bff 100644
--- a/e2fsck/super.c
+++ b/e2fsck/super.c
@@ -317,7 +317,8 @@ void check_resize_inode(e2fsck_t ctx)
 	struct problem_context	pctx;
 	int		i, gdt_off, ind_off;
 	dgrp_t		j;
-	blk64_t		blk, pblk, expect;
+	blk64_t		blk, pblk;
+	blk_t		expect;
 	__u32 		*dind_buf = 0, *ind_buf;
 	errcode_t	retval;
 
@@ -914,8 +915,7 @@ int check_backup_super_block(e2fsck_t ctx)
 		if (!ext2fs_bg_has_super(fs, g))
 			continue;
 
-		sb = fs->super->s_first_data_block +
-			(g * fs->super->s_blocks_per_group);
+		sb = ext2fs_group_first_block2(fs, g);
 
 		retval = io_channel_read_blk(fs->io, sb, -SUPERBLOCK_SIZE,
 					     buf);
diff --git a/lib/ext2fs/alloc.c b/lib/ext2fs/alloc.c
index 775dfcc..0c829ed 100644
--- a/lib/ext2fs/alloc.c
+++ b/lib/ext2fs/alloc.c
@@ -41,8 +41,7 @@ static void check_block_uninit(ext2_filsys fs, ext2fs_block_bitmap map,
 	    !(ext2fs_bg_flags_test(fs, group, EXT2_BG_BLOCK_UNINIT)))
 		return;
 
-	blk = (group * fs->super->s_blocks_per_group) +
-		fs->super->s_first_data_block;
+	blk = ext2fs_group_first_block2(fs, group);
 
 	ext2fs_super_and_bgd_loc2(fs, group, &super_blk,
 				  &old_desc_blk, &new_desc_blk, 0);
@@ -56,8 +55,7 @@ static void check_block_uninit(ext2_filsys fs, ext2fs_block_bitmap map,
 	for (i=0; i < fs->super->s_blocks_per_group; i++, blk++)
 		ext2fs_fast_unmark_block_bitmap2(map, blk);
 
-	blk = (group * fs->super->s_blocks_per_group) +
-		fs->super->s_first_data_block;
+	blk = ext2fs_group_first_block2(fs, group);
 	for (i=0; i < fs->super->s_blocks_per_group; i++, blk++) {
 		if ((blk == super_blk) ||
 		    (old_desc_blk && old_desc_blocks &&
diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index 4d6af88..9cc7cba 100644
--- a/lib/ext2fs/extent.c
+++ b/lib/ext2fs/extent.c
@@ -934,8 +934,7 @@ errcode_t ext2fs_extent_node_split(ext2_extent_handle_t handle)
 
 		if (log_flex)
 			group = group & ~((1 << (log_flex)) - 1);
-		goal_blk = (group * handle->fs->super->s_blocks_per_group) +
-			handle->fs->super->s_first_data_block;
+		goal_blk = ext2fs_group_first_block2(handle->fs, group);
 	}
 	retval = ext2fs_alloc_block2(handle->fs, goal_blk, block_buf,
 				    &new_node_pblk);
diff --git a/lib/ext2fs/mkjournal.c b/lib/ext2fs/mkjournal.c
index c154d91..c636a97 100644
--- a/lib/ext2fs/mkjournal.c
+++ b/lib/ext2fs/mkjournal.c
@@ -358,9 +358,7 @@ static errcode_t write_journal_inode(ext2_filsys fs, ext2_ino_t journal_ino,
 		    ext2fs_bg_free_blocks_count(fs, group))
 			group = i;
 
-	es.goal = (fs->super->s_blocks_per_group * group) +
-		fs->super->s_first_data_block;
-
+	es.goal = ext2fs_group_first_block2(fs, group);
 	retval = ext2fs_block_iterate3(fs, journal_ino, BLOCK_FLAG_APPEND,
 				       0, mkjournal_proc, &es);
 	if (es.err) {
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index ac965ee..8fdf35c 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -492,9 +492,8 @@ retry:
 	/*
 	 * Initialize the new block group descriptors
 	 */
-	group_block = fs->super->s_first_data_block +
-		old_fs->group_desc_count * fs->super->s_blocks_per_group;
-
+	group_block = ext2fs_group_first_block2(fs,
+						old_fs->group_desc_count);
 	csum_flag = EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 					       EXT4_FEATURE_RO_COMPAT_GDT_CSUM);
 	if (access("/sys/fs/ext4/features/lazy_itable_init", F_OK) == 0)
@@ -651,9 +650,8 @@ static errcode_t adjust_superblock(ext2_resize_t rfs, blk64_t new_size)
 		goto errout;
 
 	memset(rfs->itable_buf, 0, fs->blocksize * fs->inode_blocks_per_group);
-	group_block = fs->super->s_first_data_block +
-		rfs->old_fs->group_desc_count * fs->super->s_blocks_per_group;