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b=gyfIwML+8tY0+2IjQzdAH/pbejFKAoq8JSdQRPHsgO6HTWMHu95 oE+wBUObVYFUOQ40HFnuohrmkkOrdymxfUqceyAEMagXBbXoH9ii29ZZdGOMFdc9 UnYPnIllpoXl3DYXkoNg8G2iZpuhGd7cLfBgTTV7QU48AOBPNqUVtg3pUshGirgb 3szk3g+/S2yTWg543WCzPO9d3ut3/dVMPkEUlSo9bevhCWR+O1XyzFpH7Umbo5a1 rOadKeVDwmsEzhNwhnvleguNO6o5oxn3rXW983/SibJUvKTVWWW0grE9HoGNi6xV oXluxqVg8Yd1fJHmYVAgUqNZmK5w9exgCUw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefuddrheelgdduudelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggvpdfu rfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnh htshculddquddttddmnecujfgurhepfffhvfevuffkfhggtggujgesghdtreertddtjeen ucfhrhhomhepofgrrhgvkhcuofgrrhgtiiihkhhofihskhhiqdfikphrvggtkhhiuceomh grrhhmrghrvghksehinhhvihhsihgslhgvthhhihhnghhslhgrsgdrtghomheqnecuggft rfgrthhtvghrnhepgfduleetfeevhfefheeiteeliefhjefhleduveetteekveettddvge euteefjedunecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhho mhepmhgrrhhmrghrvghksehinhhvihhsihgslhgvthhhihhnghhslhgrsgdrtghomhdpnh gspghrtghpthhtohepiedpmhhouggvpehsmhhtphhouhhtpdhrtghpthhtohepjhgrmhgv shesughinhhgfigrlhhlrdhmvgdruhhkpdhrtghpthhtohepgigvnhdquggvvhgvlheslh hishhtshdrgigvnhdrohhrghdprhgtphhtthhopegrnhgurhgvfidrtghoohhpvghrfees tghithhrihigrdgtohhmpdhrtghpthhtohepjhgsvghulhhitghhsehsuhhsvgdrtghomh dprhgtphhtthhopehrohhgvghrrdhprghusegtihhtrhhigidrtghomhdprhgtphhtthho pehsvggtuhhrihhthiesgigvnhhprhhojhgvtghtrdhorhhg X-ME-Proxy: Feedback-ID: i1568416f:Fastmail Date: Mon, 2 Dec 2024 20:08:27 +0100 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: James Dingwall Cc: xen-devel@lists.xen.org, Andrew Cooper , Jan Beulich , Roger Pau =?utf-8?B?TW9ubsOp?= , "security@xenproject.org" Subject: Re: stable-4.18: reliably crash network driver domain by squeezing free_memory Message-ID: References: <6614df33-e383-44dd-aebc-a238ad82f398@citrix.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cbMKMcFLg4avRI/E" Content-Disposition: inline In-Reply-To: --cbMKMcFLg4avRI/E Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Mon, 2 Dec 2024 20:08:27 +0100 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: James Dingwall Cc: xen-devel@lists.xen.org, Andrew Cooper , Jan Beulich , Roger Pau =?utf-8?B?TW9ubsOp?= , "security@xenproject.org" Subject: Re: stable-4.18: reliably crash network driver domain by squeezing free_memory On Mon, Dec 02, 2024 at 03:54:23PM +0000, James Dingwall wrote: > So there is some undefined range for (free_memory - m) to (free_memory - = n) > where it is possible to crash the driver domain depending on the guest > startup ordering. My (perhaps naive) reasoning would be that > free_memory is the resource available to safely assign without having to > allow for some unknown overhead and if I do ask for too much then I > get a 'safe' failure. FWIW Qubes OS tries to always keep at least 50MB free for Xen. So, our formula is (free_memory - 50MB). --=20 Best Regards, Marek Marczykowski-G=C3=B3recki Invisible Things Lab --cbMKMcFLg4avRI/E Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhrpukzGPukRmQqkK24/THMrX1ywFAmdOBasACgkQ24/THMrX 1yxybAgAgTv8qhLuSCoOhHfNrOvAeuQ7aAmoX7xaf0b2rY6Vc9jtQMeLSXT4FbEn 0jKR94kVqDULqElpWeqgPwjldmpF1mDWNgvoDQuf85qqV+eGMOq5bROAsHH7Pt69 Uo7fh23YA7lFQl6JdcPD4+DB36eXYqEWqqaSAtZWu3iAYZhinPhHASSY4X5WFsvo C9ty8trS+lr65BN5OCZ9zhUhLfFsu3h07qsxZQn2mwQoeEHHIb4fbxTKcMQ1Zhdo l+KuUao8sr1KuwsutBac4eEmadRMPgQfWNTVofLZEkzONKYuAKXsKBnGBnZFFM1o AgSyfTiMa+bPBPA5mhP6QvWKnoYG3g== =PZEU -----END PGP SIGNATURE----- --cbMKMcFLg4avRI/E--