vfs: fix FIGETBSZ ioctl on an overlayfs file

amir73il · Miklos Szeredi · commit 8f97d1e99149 · 2018-10-26T23:34:39.000+02:00
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: d1d04ef ("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>
diff --git a/fs/ioctl.c b/fs/ioctl.c
@@ -669,6 +669,9 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 		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);
 
 	case FICLONE:
