Message ID | dd78d0a174b6c2d1560da6a02ea5e16f6eda7c8d.1535473339.git.joseph.salisbury@canonical.com |
---|---|
State | New |
Headers | show |
Series | [SRU,Trusty,1/1] ext4: fix bitmap position validation | expand |
On 31.08.2018 16:04, Joseph Salisbury wrote: > From: Lukas Czerner <lczerner@redhat.com> > > BugLink: https://bugs.launchpad.net/bugs/1789131 > > Currently in ext4_valid_block_bitmap() we expect the bitmap to be > positioned anywhere between 0 and s_blocksize clusters, but that's > wrong because the bitmap can be placed anywhere in the block group. This > causes false positives when validating bitmaps on perfectly valid file > system layouts. Fix it by checking whether the bitmap is within the group > boundary. > > The problem can be reproduced using the following > > mkfs -t ext3 -E stride=256 /dev/vdb1 > mount /dev/vdb1 /mnt/test > cd /mnt/test > wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz > tar xf linux-4.16.3.tar.xz > > This will result in the warnings in the logs > > EXT4-fs error (device vdb1): ext4_validate_block_bitmap:399: comm tar: bg 84: block 2774529: invalid block bitmap > > [ Changed slightly for clarity and to not drop a overflow test -- TYT ] > > Signed-off-by: Lukas Czerner <lczerner@redhat.com> > Signed-off-by: Theodore Ts'o <tytso@mit.edu> > Reported-by: Ilya Dryomov <idryomov@gmail.com> > Fixes: 7dac4a1726a9 ("ext4: add validity checks for bitmap block numbers") > Cc: stable@vger.kernel.org > (cherry picked from commit 22be37acce25d66ecf6403fc8f44df9c5ded2372) Acked-by: Stefan Bader <stefan.bader@canonical.com> > Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com> > Reviewed-by: Tyler Hicks <tyhicks@canonical.com> > --- > fs/ext4/balloc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c > index c19e367..7f0300f 100644 > --- a/fs/ext4/balloc.c > +++ b/fs/ext4/balloc.c > @@ -311,6 +311,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > struct ext4_sb_info *sbi = EXT4_SB(sb); > ext4_grpblk_t offset; > ext4_grpblk_t next_zero_bit; > + ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb); > ext4_fsblk_t blk; > ext4_fsblk_t group_first_block; > > @@ -328,7 +329,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > /* check whether block bitmap block number is set */ > blk = ext4_block_bitmap(sb, desc); > offset = blk - group_first_block; > - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || > + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || > !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) > /* bad block bitmap */ > return blk; > @@ -336,7 +337,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > /* check whether the inode bitmap block number is set */ > blk = ext4_inode_bitmap(sb, desc); > offset = blk - group_first_block; > - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || > + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || > !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) > /* bad block bitmap */ > return blk; > @@ -344,8 +345,8 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > /* check whether the inode table block number is set */ > blk = ext4_inode_table(sb, desc); > offset = blk - group_first_block; > - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || > - EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= sb->s_blocksize) > + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || > + EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit) > return blk; > next_zero_bit = ext4_find_next_zero_bit(bh->b_data, > EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group), >
On 08/31/18 16:04, Joseph Salisbury wrote: > From: Lukas Czerner <lczerner@redhat.com> > > BugLink: https://bugs.launchpad.net/bugs/1789131 > > Currently in ext4_valid_block_bitmap() we expect the bitmap to be > positioned anywhere between 0 and s_blocksize clusters, but that's > wrong because the bitmap can be placed anywhere in the block group. This > causes false positives when validating bitmaps on perfectly valid file > system layouts. Fix it by checking whether the bitmap is within the group > boundary. > > The problem can be reproduced using the following > > mkfs -t ext3 -E stride=256 /dev/vdb1 > mount /dev/vdb1 /mnt/test > cd /mnt/test > wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz > tar xf linux-4.16.3.tar.xz > > This will result in the warnings in the logs > > EXT4-fs error (device vdb1): ext4_validate_block_bitmap:399: comm tar: bg 84: block 2774529: invalid block bitmap > > [ Changed slightly for clarity and to not drop a overflow test -- TYT ] > > Signed-off-by: Lukas Czerner <lczerner@redhat.com> > Signed-off-by: Theodore Ts'o <tytso@mit.edu> > Reported-by: Ilya Dryomov <idryomov@gmail.com> > Fixes: 7dac4a1726a9 ("ext4: add validity checks for bitmap block numbers") > Cc: stable@vger.kernel.org > (cherry picked from commit 22be37acce25d66ecf6403fc8f44df9c5ded2372) > Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com> > Reviewed-by: Tyler Hicks <tyhicks@canonical.com> Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> > --- > fs/ext4/balloc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c > index c19e367..7f0300f 100644 > --- a/fs/ext4/balloc.c > +++ b/fs/ext4/balloc.c > @@ -311,6 +311,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > struct ext4_sb_info *sbi = EXT4_SB(sb); > ext4_grpblk_t offset; > ext4_grpblk_t next_zero_bit; > + ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb); > ext4_fsblk_t blk; > ext4_fsblk_t group_first_block; > > @@ -328,7 +329,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > /* check whether block bitmap block number is set */ > blk = ext4_block_bitmap(sb, desc); > offset = blk - group_first_block; > - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || > + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || > !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) > /* bad block bitmap */ > return blk; > @@ -336,7 +337,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > /* check whether the inode bitmap block number is set */ > blk = ext4_inode_bitmap(sb, desc); > offset = blk - group_first_block; > - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || > + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || > !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) > /* bad block bitmap */ > return blk; > @@ -344,8 +345,8 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, > /* check whether the inode table block number is set */ > blk = ext4_inode_table(sb, desc); > offset = blk - group_first_block; > - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || > - EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= sb->s_blocksize) > + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || > + EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit) > return blk; > next_zero_bit = ext4_find_next_zero_bit(bh->b_data, > EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group), >
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index c19e367..7f0300f 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -311,6 +311,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, struct ext4_sb_info *sbi = EXT4_SB(sb); ext4_grpblk_t offset; ext4_grpblk_t next_zero_bit; + ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb); ext4_fsblk_t blk; ext4_fsblk_t group_first_block; @@ -328,7 +329,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, /* check whether block bitmap block number is set */ blk = ext4_block_bitmap(sb, desc); offset = blk - group_first_block; - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) /* bad block bitmap */ return blk; @@ -336,7 +337,7 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, /* check whether the inode bitmap block number is set */ blk = ext4_inode_bitmap(sb, desc); offset = blk - group_first_block; - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) /* bad block bitmap */ return blk; @@ -344,8 +345,8 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, /* check whether the inode table block number is set */ blk = ext4_inode_table(sb, desc); offset = blk - group_first_block; - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || - EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= sb->s_blocksize) + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || + EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit) return blk; next_zero_bit = ext4_find_next_zero_bit(bh->b_data, EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),