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Tue, 05 May 2026 08:52:06 -0700 (PDT) Date: Tue, 5 May 2026 15:52:05 +0000 From: Pasha Tatashin To: Hugh Dickins , Baolin Wang , Andrew Morton , Jeff Xu , Kees Cook , Pratyush Yadav Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Brendan Jackman , Greg Thelen , stable@vger.kernel.org Subject: Re: [PATCH] memfd: deny writeable mappings when implying SEAL_WRITE Message-ID: References: <20260505133922.797635-1-pratyush@kernel.org> <177799542165.635180.17809433268620237886.b4-ty@soleen.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <177799542165.635180.17809433268620237886.b4-ty@soleen.com> On 05-05 15:37, Pasha Tatashin wrote: > > On Tue, 05 May 2026 15:39:20 +0200, Pratyush Yadav wrote: > > When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the > > implied seal is set after the check that makes sure the memfd can not > > have any writable mappings. This means one can use SEAL_EXEC to apply > > SEAL_WRITE while having writeable mappings. > > > > This breaks the contract that SEAL_WRITE provides and can be used by an > > attacker to pass a memfd that appears to be write sealed but can still > > be modified arbitrarily. > > > > [...] > > Applied, thanks! > > [1/1] memfd: deny writeable mappings when implying SEAL_WRITE > commit: 73f496662a9848021e75742a69a3239ea850c3ee ^^^ Please ignore, this should be Applied to MM tree. Pasha > > Best regards, > -- > Pasha Tatashin >