linux-kernel - Re: [syzbot] [fuse?] kernel BUG in fuse_dev_do

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Message-Id: <20241020093903.2182-1-hdanton@sina.com>
Date: Sun, 20 Oct 2024 17:39:03 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+65d101735df4bb19d2a3@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [fuse?] kernel BUG in fuse_dev_do_write

On Sun, 20 Oct 2024 01:11:37 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    15e7d45e786a Add linux-next specific files for 20241016
> git tree:       linux-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16582f27980000

#syz test

--- x/fs/fuse/dev.c
+++ y/fs/fuse/dev.c
@@ -1668,7 +1668,7 @@ static int fuse_notify_store(struct fuse
 		err = fuse_copy_page(cs, &page, offset, this_num, 0);
 		if (!folio_test_uptodate(folio) && !err && offset == 0 &&
 		    (this_num == folio_size(folio) || file_size == end)) {
-			folio_zero_range(folio, this_num, folio_size(folio));
+			folio_zero_range(folio, this_num, folio_size(folio) - this_num);
 			folio_mark_uptodate(folio);
 		}
 		folio_unlock(folio);
--