Re: [syzbot] Re: [syzbot] [block?] BUG: unable to handle kernel NULL pointer dereference in lo_rw_aio

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@xxxxxxxxxxxxxxx.

***

Subject: Re: [syzbot] [block?] BUG: unable to handle kernel NULL pointer dereference in lo_rw_aio
Author: lizhi.xu@xxxxxxxxxxxxx

selinux policy not support read_iter

#syz test

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4f968e3071ed..3572b50dbf0a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1044,6 +1044,10 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
 
 	if (!file)
 		return -EBADF;
+
+	if (unlikely(!file->f_op->read_iter))
+		return -EINVAL;
+
 	is_loop = is_loop_device(file);
 
 	/* This is safe, since we have a reference from open(). */