77 lines
3.2 KiB
Diff
77 lines
3.2 KiB
Diff
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From: Lukas Czerner <lczerner@redhat.com>
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Date: Tue, 24 Apr 2018 11:31:44 -0400
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Subject: ext4: fix bitmap position validation
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Origin: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit?id=22be37acce25d66ecf6403fc8f44df9c5ded2372
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Currently in ext4_valid_block_bitmap() we expect the bitmap to be
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positioned anywhere between 0 and s_blocksize clusters, but that's
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wrong because the bitmap can be placed anywhere in the block group. This
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causes false positives when validating bitmaps on perfectly valid file
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system layouts. Fix it by checking whether the bitmap is within the group
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boundary.
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The problem can be reproduced using the following
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mkfs -t ext3 -E stride=256 /dev/vdb1
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mount /dev/vdb1 /mnt/test
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cd /mnt/test
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wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz
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tar xf linux-4.16.3.tar.xz
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This will result in the warnings in the logs
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EXT4-fs error (device vdb1): ext4_validate_block_bitmap:399: comm tar: bg 84: block 2774529: invalid block bitmap
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[ Changed slightly for clarity and to not drop a overflow test -- TYT ]
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Signed-off-by: Lukas Czerner <lczerner@redhat.com>
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Reported-by: Ilya Dryomov <idryomov@gmail.com>
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Fixes: 7dac4a1726a9 ("ext4: add validity checks for bitmap block numbers")
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Cc: stable@vger.kernel.org
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---
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fs/ext4/balloc.c | 9 +++++----
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1 file changed, 5 insertions(+), 4 deletions(-)
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diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
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index a33d8fb1bf2a..508b905d744d 100644
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--- a/fs/ext4/balloc.c
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+++ b/fs/ext4/balloc.c
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@@ -321,6 +321,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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ext4_grpblk_t offset;
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ext4_grpblk_t next_zero_bit;
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+ ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
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ext4_fsblk_t blk;
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ext4_fsblk_t group_first_block;
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@@ -338,7 +339,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
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/* check whether block bitmap block number is set */
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blk = ext4_block_bitmap(sb, desc);
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offset = blk - group_first_block;
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- if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
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+ if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
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!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
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/* bad block bitmap */
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return blk;
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@@ -346,7 +347,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
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/* check whether the inode bitmap block number is set */
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blk = ext4_inode_bitmap(sb, desc);
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offset = blk - group_first_block;
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- if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
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+ if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
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!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
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/* bad block bitmap */
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return blk;
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@@ -354,8 +355,8 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
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/* check whether the inode table block number is set */
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blk = ext4_inode_table(sb, desc);
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offset = blk - group_first_block;
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- if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
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- EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= sb->s_blocksize)
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+ if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
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+ EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
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return blk;
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next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
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EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
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