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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 7 Dec 2023 13:38:23 +0100
Message-ID: <CANn89i+KiP+=WzXJvqTjRt1a3GNr1iyn+BTAJ0puYbOLkC+cHA@mail.gmail.com>
Subject: Re: [syzbot] [net?] KMSAN: uninit-value in ipgre_xmit
To:     xingwei lee <xrivendell7@gmail.com>
Cc:     davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        pabeni@redhat.com, syoshida@redhat.com,
        syzbot+2cb7b1bd08dc77ae7f89@syzkaller.appspotmail.com,
        syzkaller-bugs@googlegroups.com
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On Thu, Dec 7, 2023 at 6:03=E2=80=AFAM xingwei lee <xrivendell7@gmail.com> =
wrote:
>
> Hello Eric.
> I reproduced this bug with repro.c and repro.txt
> HEAD commit: 815fb87b753055df2d9e50f6cd80eb10235fe3e9
> kernel config: https://syzkaller.appspot.com/text?tag=3DKernelConfig&x=3D=
f711bc2a7eb1db25
> as the same in https://syzkaller.appspot.com/bug?extid=3D2cb7b1bd08dc77ae=
7f89
>

I think the patch has been merged in net tree, thanks.

commit 80d875cfc9d3711a029f234ef7d680db79e8fa4b
Author:     Shigeru Yoshida <syoshida@redhat.com>
AuthorDate: Sun Dec 3 01:14:41 2023 +0900
Commit:     Paolo Abeni <pabeni@redhat.com>
CommitDate: Wed Dec 6 10:08:05 2023 +0100

    ipv4: ip_gre: Avoid skb_pull() failure in ipgre_xmit()

    In ipgre_xmit(), skb_pull() may fail even if pskb_inet_may_pull() retur=
ns
    true. For example, applications can use PF_PACKET to create a malformed
    packet with no IP header. This type of packet causes a problem such as
    uninit-value access.

    This patch ensures that skb_pull() can pull the required size by checki=
ng
    the skb with pskb_network_may_pull() before skb_pull().

    Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
    Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
    Reviewed-by: Eric Dumazet <edumazet@google.com>
    Reviewed-by: Suman Ghosh <sumang@marvell.com>
    Link: https://lore.kernel.org/r/20231202161441.221135-1-syoshida@redhat=
.com
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>