From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 77036352FBB for ; Fri, 30 Jan 2026 11:24:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769772281; cv=none; b=Fsv9VbCILWQ8YdiiyvmOcaM7Y5tUc6jRO3yQS3SbZahguKzDnvRrYynrv+0s/BZsiVLp0MauhFOpULezIOop3JCfct1/I4qz0LRq+09xS6ZaXPZi+O4+yS6xA0AEOJ5mRNPQ3BOyiRAWbQywyX8xvnUGfk1Jzv0oz0X6FCQdrQA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769772281; c=relaxed/simple; bh=//89rM1aPwdgXoJn9DcajFm18MPvI46EoIZOzCrcGgg=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=vA+VbNpE7n0+WpfrldVdwrW4ZqCcEEcf2KZHdkxCEx0Rm6oXFZ/2RuiSYavmAl2S72BsOQfJPz1KXmD5fcIWziC5vQQDplkbEw71l0a0gNavGc8Nj0WlCFH466i1Wx1aXmEY/r5nVgRaXU9A62+OprbXchDe6A9xlzfWqUqvNNQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pe4klZh0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Pe4klZh0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E3DCC4CEF7; Fri, 30 Jan 2026 11:24:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769772281; bh=//89rM1aPwdgXoJn9DcajFm18MPvI46EoIZOzCrcGgg=; h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=Pe4klZh0k4w3zpMl6NNmqJsiS0M93KumuUQtKY37RLkgJfZOQpDmytBY6Imarro7g cgle87VpaMVaXntVJKbGrlRsXxF9U2HsTMESer0elYEAXBMhRlCAb+I3WCEMxa5xWV JmInZ7RyVlu0+zo9MTavEDe0Ha5YwwnWyBETyQGLXBC0NWnPWg0tTw8qhKYN5KXqV4 P7VZvqob9EE6B/tPzBCN7atLtuYKAHRSq5GodqKj05c8Q0o4xVct8ye3iiVs3DLiv0 /e4RYgQXniccnGk3qOs5LSzFhcR/+1EmY7f6v4qVoya6diWh/ScHYvKyPvFl1lQuTe 28eVZoYKMawHA== Message-ID: Date: Fri, 30 Jan 2026 12:24:38 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mptcp-net 1/2] mptcp: pm: in-kernel: always set as unavail when removing addr Content-Language: en-GB, fr-BE From: Matthieu Baerts To: Mat Martineau Cc: MPTCP Upstream , syzbot+f56f7d56e2c6e11a01b6@syzkaller.appspotmail.com References: <20251215-issue-606-mark-subflow-endp-avail-v1-0-2f1b36da8993@kernel.org> <20251215-issue-606-mark-subflow-endp-avail-v1-1-2f1b36da8993@kernel.org> <2059f374-0447-30ff-92ff-b090fd91504d@kernel.org> Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Mat, On 26/01/2026 19:34, Matthieu Baerts wrote: > Hi Mat, > > Thank you for the review! > > On 15/01/2026 05:56, Mat Martineau wrote: >> On Mon, 15 Dec 2025, Matthieu Baerts (NGI0) wrote: >> >>> Syzkaller managed to find a combination of actions that was generating >>> this warning: > > (...) > >>> diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c >>> index f59d21e7579c..51bcfcec882d 100644 >>> --- a/net/mptcp/pm_kernel.c >>> +++ b/net/mptcp/pm_kernel.c >>> @@ -1057,10 +1057,8 @@ static bool mptcp_pm_remove_anno_addr(struct >>> mptcp_sock *msk, >>>     ret = mptcp_remove_anno_list_by_saddr(msk, addr); >>>     if (ret || force) { >>>         spin_lock_bh(&msk->pm.lock); >>> -        if (ret) { >>> -            __set_bit(addr->id, msk->pm.id_avail_bitmap); >>> +        if (ret) >>>             msk->pm.add_addr_signaled--; >>> -        } >>>         mptcp_pm_remove_addr(msk, &list); >>>         spin_unlock_bh(&msk->pm.lock); >>>     } >>> @@ -1098,17 +1096,14 @@ static int >>> mptcp_nl_remove_subflow_and_signal_addr(struct net *net, >>>                       !(entry->flags & MPTCP_PM_ADDR_FLAG_IMPLICIT)); >>> >>>         list.ids[0] = mptcp_endp_get_local_id(msk, addr); >>> -        if (remove_subflow) { >>> -            spin_lock_bh(&msk->pm.lock); >>> -            mptcp_pm_rm_subflow(msk, &list); >>> -            spin_unlock_bh(&msk->pm.lock); >>> -        } >>> >>> -        if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) { >>> -            spin_lock_bh(&msk->pm.lock); >>> +        spin_lock_bh(&msk->pm.lock); >>> +        if (remove_subflow) >>> +            mptcp_pm_rm_subflow(msk, &list); >>> +        if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) >>>             __mark_subflow_endp_available(msk, list.ids[0]); >>> -            spin_unlock_bh(&msk->pm.lock); >>> -        } >>> +        __set_bit(addr->id, msk->pm.id_avail_bitmap); >> >> There's not any harm in setting this bit a second time if it was also >> set in __mark_subflow_endp_available(). >> >> However, __mark_subflow_endp_available() has some logic around ID 0 and >> mpc_endpoint_id. Is that relevant in this code path or is the new >> __set_bit() doing the correct thing by always clearing based on addr->id? > > Good point. Even if there is no harm, no need to set the bit for ID 0. I > will look at that! I just re-checked this: addr->id here is always positive because that's the endpoint ID, not the ID used on the wire (list.ids[0]) which can be 0 if this endpoint is linked to the initial subflow. So we don't need the same logic around ID 0 and mpc_endpoint_id. Still, I can add this before calling __set_bit() not to clear the bit a second time: else /* mark endp ID as available, e.g. Signal or MPC endp */ Cheers, Matt -- Sponsored by the NGI0 Core fund.