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| author |   Lukas Czerner <lczerner@redhat.com> | 2022-07-04 16:27:21 +0200 |
|---|---|---|
| committer |   Theodore Ts'o <tytso@mit.edu> | 2022-08-02 23:56:17 -0400 |
| commit | b8a04fe77ef1360fbf73c80fddbdfeaa9407ed1b (patch) | |
| tree | 504a79dafe61d776611aa4ea5715b2d18337b40f | |
| parent | ext4: check if directory block is within i_size (diff) | |
| download | linux-dev-b8a04fe77ef1360fbf73c80fddbdfeaa9407ed1b.tar.xz linux-dev-b8a04fe77ef1360fbf73c80fddbdfeaa9407ed1b.zip | |
ext4: make sure ext4_append() always allocates new block
ext4_append() must always allocate a new block, otherwise we run the
risk of overwriting existing directory block corrupting the directory
tree in the process resulting in all manner of problems later on.
Add a sanity check to see if the logical block is already allocated and
error out if it is.
Cc: stable@kernel.org
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20220704142721.157985-2-lczerner@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/namei.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 7fced54e2891..3a31b662f661 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -54,6 +54,7 @@ static struct buffer_head *ext4_append(handle_t *handle, struct inode *inode, ext4_lblk_t *block) { + struct ext4_map_blocks map; struct buffer_head *bh; int err; @@ -63,6 +64,21 @@ static struct buffer_head *ext4_append(handle_t *handle, return ERR_PTR(-ENOSPC); *block = inode->i_size >> inode->i_sb->s_blocksize_bits; + map.m_lblk = *block; + map.m_len = 1; + + /* + * We're appending new directory block. Make sure the block is not + * allocated yet, otherwise we will end up corrupting the + * directory. + */ + err = ext4_map_blocks(NULL, inode, &map, 0); + if (err < 0) + return ERR_PTR(err); + if (err) { + EXT4_ERROR_INODE(inode, "Logical block already allocated"); + return ERR_PTR(-EFSCORRUPTED); + } bh = ext4_bread(handle, inode, *block, EXT4_GET_BLOCKS_CREATE); if (IS_ERR(bh)) |