linux-kernel - Re: [syzbot] WARNING in iomap

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Message-ID: <20220823153542.177799-1-code@siddh.me>
Date:   Tue, 23 Aug 2022 21:05:42 +0530
From:   Siddh Raman Pant <code@...dh.me>
To:     willy@...radead.org
Cc:     code@...dh.me, david@...morbit.com, djwong@...nel.org,
        fgheet255t@...il.com, hch@...radead.org,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        riteshh@...ux.ibm.com,
        syzbot+a8e049cd3abd342936b6@...kaller.appspotmail.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] WARNING in iomap_iter

Oof, I didn't mean it to be there. That would actually be wrong anyways.

Extremely sorry for the avoidable oversight,
Siddh

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 drivers/block/loop.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e3c0ba93c1a3..e1fe8eda020f 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -979,6 +979,11 @@ loop_set_status_from_info(struct loop_device *lo,
 
 	lo->lo_offset = info->lo_offset;
 	lo->lo_sizelimit = info->lo_sizelimit;
+
+	/* loff_t vars have been assigned __u64 */
+	if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
+		return -EOVERFLOW;
+
 	memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
 	lo->lo_file_name[LO_NAME_SIZE-1] = 0;
 	lo->lo_flags = info->lo_flags;
-- 
2.35.1