From: Simon Horman <horms@kernel.org>
To: Ranganath V N <vnranganath.20@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
skhan@linuxfoundation.org, david.hunter.linux@gmail.com,
khalid@kernel.org,
syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com
Subject: Re: [PATCH v2 0/2] net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak
Date: Tue, 4 Nov 2025 14:08:10 +0000 [thread overview]
Message-ID: <aQoIygv-7h4m21SG@horms.kernel.org> (raw)
In-Reply-To: <20251101-infoleak-v2-0-01a501d41c09@gmail.com>
On Sat, Nov 01, 2025 at 06:04:46PM +0530, Ranganath V N wrote:
> Fix a KMSAN kernel-infoleak detected by the syzbot .
>
> [net?] KMSAN: kernel-infoleak in __skb_datagram_iter
>
> In tcf_ife_dump(), the variable 'opt' was partially initialized using a
> designatied initializer. While the padding bytes are reamined
> uninitialized. nla_put() copies the entire structure into a
> netlink message, these uninitialized bytes leaked to userspace.
>
> Initialize the structure with memset before assigning its fields
> to ensure all members and padding are cleared prior to beign copied.
Perhaps not important, but this seems to only describe patch 1/2.
>
> Signed-off-by: Ranganath V N <vnranganath.20@gmail.com>
Sorry for not looking more carefully at v1.
The presence of this padding seems pretty subtle to me.
And while I agree that your change fixes the problem described.
I wonder if it would be better to make things more obvious
by adding a 2-byte pad member to the structures involved.
...
next prev parent reply other threads:[~2025-11-04 14:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-01 12:34 [PATCH v2 0/2] net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak Ranganath V N
2025-11-01 12:34 ` [PATCH v2 1/2] " Ranganath V N
2025-11-04 14:10 ` Simon Horman
2025-11-01 12:34 ` [PATCH v2 2/2] net: sched: act_connmark: zero initialize the struct to avoid KMSAN Ranganath V N
2025-11-04 14:08 ` Simon Horman [this message]
2025-11-05 10:03 ` [PATCH v2 0/2] net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak Ranganath V N
2025-11-05 12:59 ` Simon Horman
2025-11-05 15:09 ` Jamal Hadi Salim
2025-11-05 19:13 ` Simon Horman
2025-11-06 13:31 ` Ranganath V N
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