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Subject[PATCH 15/49] ext4: store maxbytes for bitmapped files and return EFBIG as appropriate
Date
From: Eric Sandeen <sandeen@redhat.com>

Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
fs/ext4/file.c | 19 ++++++++++++++++++-
fs/ext4/inode.c | 16 +++++++++++++++-
fs/ext4/super.c | 1 +
include/linux/ext4_fs_sb.h | 1 +
4 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1a81cd6..a6b2aa1 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -56,8 +56,25 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
ssize_t ret;
int err;

- ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+ /*
+ * If we have encountered a bitmap-format file, the size limit
+ * is smaller than s_maxbytes, which is for extent-mapped files.
+ */
+
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ size_t length = iov_length(iov, nr_segs);

+ if (pos > sbi->s_bitmap_maxbytes)
+ return -EFBIG;
+
+ if (pos + length > sbi->s_bitmap_maxbytes) {
+ nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
+ sbi->s_bitmap_maxbytes - pos);
+ }
+ }
+
+ ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
/*
* Skip flushing if there was an error, or if nothing was written.
*/
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9cf8572..eaace13 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -314,7 +314,10 @@ static int ext4_block_to_path(struct inode *inode,
offsets[n++] = i_block & (ptrs - 1);
final = ptrs;
} else {
- ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");
+ ext4_warning(inode->i_sb, "ext4_block_to_path",
+ "block %u > max",
+ i_block + direct_blocks +
+ indirect_blocks + double_blocks);
}
if (boundary)
*boundary = final - 1 - (i_block & (ptrs - 1));
@@ -3092,6 +3095,17 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
ext4_journal_stop(handle);
}

+ if (attr->ia_valid & ATTR_SIZE) {
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+ if (attr->ia_size > sbi->s_bitmap_maxbytes) {
+ error = -EFBIG;
+ goto err_out;
+ }
+ }
+ }
+
if (S_ISREG(inode->i_mode) &&
attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
handle_t *handle;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c79e46b..0931831 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1922,6 +1922,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
}
}

+ sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits);
sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits);

if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
diff --git a/include/linux/ext4_fs_sb.h b/include/linux/ext4_fs_sb.h
index f15821c..38a47ec 100644
--- a/include/linux/ext4_fs_sb.h
+++ b/include/linux/ext4_fs_sb.h
@@ -38,6 +38,7 @@ struct ext4_sb_info {
ext4_group_t s_groups_count; /* Number of groups in the fs */
unsigned long s_overhead_last; /* Last calculated overhead */
unsigned long s_blocks_last; /* Last seen block count */
+ loff_t s_bitmap_maxbytes; /* max bytes for bitmap files */
struct buffer_head * s_sbh; /* Buffer containing the super block */
struct ext4_super_block * s_es; /* Pointer to the super block in the buffer */
struct buffer_head ** s_group_desc;
--
1.5.4.rc3.31.g1271-dirty


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