linux-kernel - Re: [syzbot] [comedi?] KMSAN: kernel-infoleak in do_insnlist

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Message-ID: <20250731093913.3644-1-hdanton@sina.com>
Date: Thu, 31 Jul 2025 17:39:12 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+fb4362a104d45ab09cf9@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [comedi?] KMSAN: kernel-infoleak in do_insnlist_ioctl

> Date: Thu, 31 Jul 2025 00:29:38 -0700	[thread overview]
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    e8d780dcd957 Merge tag 'slab-for-6.17' of git://git.kernel..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=154b8f82580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=30a934bba3cd727
> dashboard link: https://syzkaller.appspot.com/bug?extid=fb4362a104d45ab09cf9
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10a04ca2580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13a269bc580000

#syz test

--- x/drivers/comedi/comedi_fops.c
+++ y/drivers/comedi/comedi_fops.c
@@ -1566,7 +1566,7 @@ static int do_insnlist_ioctl(struct come
 
 	/* Allocate scratch space for all instruction data. */
 	data = kmalloc_array(max_n_data_required, sizeof(unsigned int),
-			     GFP_KERNEL);
+			     GFP_KERNEL | __GFP_ZERO);
 	if (!data) {
 		ret = -ENOMEM;
 		goto error;
--