[ALPS04224662] ext4: only look at the bg_flags field if it is valid

The bg_flags field in the block group descripts is only valid if the
uninit_bg or metadata_csum feature is enabled.  We were not
consistently looking at this field; fix this.

Also block group #0 must never have uninitialized allocation bitmaps,
or need to be zeroed, since that's where the root inode, and other
special inodes are set up.  Check for these conditions and mark the
file system as corrupted if they are detected.

https://bugzilla.kernel.org/show_bug.cgi?id=199403

Change-Id: I38be36618636178b45bb0ef7cbb8e5802565a2e9
Signed-off-by: Light Hsieh <light.hsieh@mediatek.com>
CR-Id: ALPS04224662
Feature: [Android Default] EXT4 File System
(cherry picked from commit b6be4f963e8338bdaea88ceb210617cc2dc7d1e8)
(cherry picked from commit 9f9aaa9aede02177d390cda2c6588ebf027a29dc)
(cherry-pick from 3517f9a079a0575fe3a2086f3e07d6d3ea8c390a)

4 files changed, 39 insertions, 50 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index f97110461c19..01cc9575e98f 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -242,8 +242,6 @@ static int ext4_init_block_bitmap(struct super_block *sb,
 	 */
 	ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 			     sb->s_blocksize * 8, bh->b_data);
-	ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
-	ext4_group_desc_csum_set(sb, block_group, gdp);
 	return 0;
 }
 
@@ -443,10 +441,20 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 		goto verify;
 	}
 	ext4_lock_group(sb, block_group);
-	if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
+	if (ext4_has_group_desc_csum(sb) &&
+	    (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
+		if (block_group == 0) {
+			ext4_unlock_group(sb, block_group);
+			unlock_buffer(bh);
+			ext4_error(sb,
+				"Block bitmap for bg 0 marked uninitialized");
+			err = -EIO;
+			goto out;
+		}
 		err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 		set_bitmap_uptodate(bh);
 		set_buffer_uptodate(bh);
+		set_buffer_verified(bh);
 		ext4_unlock_group(sb, block_group);
 		unlock_buffer(bh);
 		if (err) {
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 5388207d2832..29b989973539 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -63,44 +63,6 @@ void ext4_mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 		memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 }
 
-/* Initializes an uninitialized inode bitmap */
-static int ext4_init_inode_bitmap(struct super_block *sb,
-				       struct buffer_head *bh,
-				       ext4_group_t block_group,
-				       struct ext4_group_desc *gdp)
-{
-	struct ext4_group_info *grp;
-	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	J_ASSERT_BH(bh, buffer_locked(bh));
-
-	/* If checksum is bad mark all blocks and inodes use to prevent
-	 * allocation, essentially implementing a per-group read-only flag. */
-	if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
-		grp = ext4_get_group_info(sb, block_group);
-		if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
-			percpu_counter_sub(&sbi->s_freeclusters_counter,
-					   grp->bb_free);
-		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
-		if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
-			int count;
-			count = ext4_free_inodes_count(sb, gdp);
-			percpu_counter_sub(&sbi->s_freeinodes_counter,
-					   count);
-		}
-		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
-		return -EFSBADCRC;
-	}
-
-	memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
-	ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
-			bh->b_data);
-	ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,
-				   EXT4_INODES_PER_GROUP(sb) / 8);
-	ext4_group_desc_csum_set(sb, block_group, gdp);
-
-	return 0;
-}
-
 void ext4_end_bitmap_read(struct buffer_head *bh, int uptodate)
 {
 	if (uptodate) {
@@ -157,6 +119,7 @@ static struct buffer_head *
 ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 {
 	struct ext4_group_desc *desc;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct buffer_head *bh = NULL;
 	ext4_fsblk_t bitmap_blk;
 	int err;
@@ -166,6 +129,13 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 		return ERR_PTR(-EFSCORRUPTED);
 
 	bitmap_blk = ext4_inode_bitmap(sb, desc);
+	if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
+	    (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
+		ext4_error(sb,
+			   "Invalid inode bitmap blk %llu in block_group %u",
+			   bitmap_blk, block_group);
+		return ERR_PTR(-EUCLEAN);
+	}
 	bh = sb_getblk(sb, bitmap_blk);
 	if (unlikely(!bh)) {
 		ext4_error(sb, "Cannot read inode bitmap - "
@@ -183,18 +153,24 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 	}
 
 	ext4_lock_group(sb, block_group);
-	if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
-		err = ext4_init_inode_bitmap(sb, bh, block_group, desc);
+	if (ext4_has_group_desc_csum(sb) &&
+	    (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT))) {
+		if (block_group == 0) {
+			ext4_unlock_group(sb, block_group);
+			unlock_buffer(bh);
+			ext4_error(sb,
+				"Inode bitmap for bg 0 marked uninitialized");
+			err = -EFSCORRUPTED;
+			goto out;
+		}
+		memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
+		ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
+				     sb->s_blocksize * 8, bh->b_data);
 		set_bitmap_uptodate(bh);
 		set_buffer_uptodate(bh);
 		set_buffer_verified(bh);
 		ext4_unlock_group(sb, block_group);
 		unlock_buffer(bh);
-		if (err) {
-			ext4_error(sb, "Failed to init inode bitmap for group "
-				   "%u: %d", block_group, err);
-			goto out;
-		}
 		return bh;
 	}
 	ext4_unlock_group(sb, block_group);
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c2810503eb50..3f05ea81493a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2443,7 +2443,8 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
 	 * initialize bb_free to be able to skip
 	 * empty groups without initialization
 	 */
-	if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
+	if (ext4_has_group_desc_csum(sb) &&
+	    (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
 		meta_group_info[i]->bb_free =
 			ext4_free_clusters_after_init(sb, group, desc);
 	} else {
@@ -2965,7 +2966,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 #endif
 	ext4_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
 		      ac->ac_b_ex.fe_len);
-	if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
+	if (ext4_has_group_desc_csum(sb) &&
+	    (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
 		gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
 		ext4_free_group_clusters_set(sb, gdp,
 					     ext4_free_clusters_after_init(sb,
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 05668999f6e4..c64b9923af74 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2847,6 +2847,9 @@ static ext4_group_t ext4_has_uninit_itable(struct super_block *sb)
 	ext4_group_t group, ngroups = EXT4_SB(sb)->s_groups_count;
 	struct ext4_group_desc *gdp = NULL;
 
+	if (!ext4_has_group_desc_csum(sb))
+		return ngroups;
+
 	for (group = 0; group < ngroups; group++) {
 		gdp = ext4_get_group_desc(sb, group, NULL);
 		if (!gdp)