[PATCH 4.19 063/205] vfs: fix FIGETBSZ ioctl on an overlayfs file

Greg Kroah-Hartman
2018-11-19T16:33:12Z

From: Amir Goldstein <amir73il@gmail.com>

commit 8f97d1e99149a7f1aa19e47a51b09764382a482e upstream.

Some anon_bdev filesystems (e.g. overlayfs, ceph) don't have s_blocksize
set. Returning zero from FIGETBSZ ioctl results in a Floating point
exception from the e2fsprogs utility filefrag, which divides the size of
the file with the value returned by FIGETBSZ.

Fix the interface by returning -EINVAL for these filesystems.

Fixes: d1d04ef8572b ("ovl: stack file ops")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ioctl.c | 3 +++
1 file changed, 3 insertions(+)

--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -669,6 +669,9 @@ int do_vfs_ioctl(struct file *filp, unsi
return ioctl_fiemap(filp, arg);

case FIGETBSZ:
+ /* anon_bdev filesystems may not have a block size */
+ if (!inode->i_sb->s_blocksize)
+ return -EINVAL;
return put_user(inode->i_sb->s_blocksize, argp);