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

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Date:   Sun, 21 Aug 2022 17:18:16 +0530
From:   Siddh Raman Pant <code@...dh.me>
To:     code@...dh.me
Cc:     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, willy@...radead.org
Subject: Re: [syzbot] WARNING in iomap_iter

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

---
 drivers/block/loop.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e3c0ba93c1a3..a3d9af0a2077 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -979,9 +979,15 @@ loop_set_status_from_info(struct loop_device *lo,
 
 	lo->lo_offset = info->lo_offset;
 	lo->lo_sizelimit = info->lo_sizelimit;
+	lo->lo_flags = info->lo_flags;
+
+	/* loff_t/int vars are assigned __u64/__u32 vars (respectively) */
+	if (lo->lo_offset < 0 || lo->lo_sizelimit < 0 || lo->lo_flags < 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;
+
 	return 0;
 }
 
-- 
2.35.1