diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2018-04-16 23:07:45 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-09 09:50:21 +0200 |
| commit | b13d8f52b8e7f713196e7fc643b44a72ad3da1be (patch) | |
| tree | 7f0cea5f0e5c98c27a434a9dcc9ee8dcb8e3a874 | |
| parent | c0ff32016565d4332e4012b82105918e4c28d4ea (diff) | |
xfs: prevent creating negative-sized file via INSERT_RANGE
commit 7d83fb14258b9961920cd86f0b921caaeb3ebe85 upstream.
During the "insert range" fallocate operation, i_size grows by the
specified 'len' bytes. XFS verifies that i_size + len < s_maxbytes, as
it should. But this comparison is done using the signed 'loff_t', and
'i_size + len' can wrap around to a negative value, causing the check to
incorrectly pass, resulting in an inode with "negative" i_size. This is
possible on 64-bit platforms, where XFS sets s_maxbytes = LLONG_MAX.
ext4 and f2fs don't run into this because they set a smaller s_maxbytes.
Fix it by using subtraction instead.
Reproducer:
xfs_io -f file -c "truncate $(((1<<63)-1))" -c "finsert 0 4096"
Fixes: a904b1ca5751 ("xfs: Add support FALLOC_FL_INSERT_RANGE for fallocate")
Cc: <stable@vger.kernel.org> # v4.1+
Originally-From: Eric Biggers <ebiggers@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: fix signed integer addition overflow too]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/xfs/xfs_file.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 362c6b4c1186..1410835eebe2 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -846,22 +846,26 @@ xfs_file_fallocate( if (error) goto out_unlock; } else if (mode & FALLOC_FL_INSERT_RANGE) { - unsigned int blksize_mask = i_blocksize(inode) - 1; + unsigned int blksize_mask = i_blocksize(inode) - 1; + loff_t isize = i_size_read(inode); - new_size = i_size_read(inode) + len; if (offset & blksize_mask || len & blksize_mask) { error = -EINVAL; goto out_unlock; } - /* check the new inode size does not wrap through zero */ - if (new_size > inode->i_sb->s_maxbytes) { + /* + * New inode size must not exceed ->s_maxbytes, accounting for + * possible signed overflow. + */ + if (inode->i_sb->s_maxbytes - isize < len) { error = -EFBIG; goto out_unlock; } + new_size = isize + len; /* Offset should be less than i_size */ - if (offset >= i_size_read(inode)) { + if (offset >= isize) { error = -EINVAL; goto out_unlock; } |