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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Theodore Ts'o" <tytso@mit.edu>
Date:   Sat, 22 Sep 2018 01:15:42 +0100
Message-ID: <lsq.1537575342.123314101@decadent.org.uk>
Subject: [PATCH 3.16 27/63] ext4: always check block group bounds in
 ext4_init_block_bitmap()
In-Reply-To: <lsq.1537575341.194909669@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.58-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 819b23f1c501b17b9694325471789e6b5cc2d0d2 upstream.

Regardless of whether the flex_bg feature is set, we should always
check to make sure the bits we are setting in the block bitmap are
within the block group bounds.

https://bugzilla.kernel.org/show_bug.cgi?id=199865

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/ext4/balloc.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -184,7 +184,6 @@ static int ext4_init_block_bitmap(struct
 	unsigned int bit, bit_max;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	ext4_fsblk_t start, tmp;
-	int flex_bg = 0;
 	struct ext4_group_info *grp;
 
 	J_ASSERT_BH(bh, buffer_locked(bh));
@@ -217,22 +216,19 @@ static int ext4_init_block_bitmap(struct
 
 	start = ext4_group_first_block_no(sb, block_group);
 
-	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
-		flex_bg = 1;
-
 	/* Set bits for block and inode bitmaps, and inode table */
 	tmp = ext4_block_bitmap(sb, gdp);
-	if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
+	if (ext4_block_in_group(sb, tmp, block_group))
 		ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 
 	tmp = ext4_inode_bitmap(sb, gdp);
-	if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
+	if (ext4_block_in_group(sb, tmp, block_group))
 		ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 
 	tmp = ext4_inode_table(sb, gdp);
 	for (; tmp < ext4_inode_table(sb, gdp) +
 		     sbi->s_itb_per_group; tmp++) {
-		if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
+		if (ext4_block_in_group(sb, tmp, block_group))
 			ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 	}