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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20260720145631.201053-2-horms@kernel.org> References: <20260720145631.201053-2-horms@kernel.org> <20260713081022.2186481-15-dhowells@redhat.com> To: Simon Horman Cc: dhowells@redhat.com, netdev@vger.kernel.org, marc.dionne@auristor.com, kuba@kernel.org, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org, stable@kernel.org Subject: Re: [PATCH net v3 14/14] rxrpc: Remove OOB challenge/response code Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <423992.1784795410.1@warthog.procyon.org.uk> Date: Thu, 23 Jul 2026 09:30:10 +0100 Message-ID: <423993.1784795410@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Simon Horman wrote: > [Severity: Critical] > Does removing these constants from the UAPI header violate the kernel's > policy against breaking userspace? > > Any userspace program that includes linux/rxrpc.h and references the > removed RXRPC_OOB_ID or related constants will now fail to compile. > ... > [Severity: Critical] > Does this change break backwards compatibility for existing applications? Yep. I explained my justification for that in the cover. I don't expect anything outside of my own tools to use the API, plus this particular facet of the API has only been around for a short time. Further, the underlying mechanism in the kernel is replaced here, so the OOB challenge-response API is no longer effective. > [Severity: Critical] > Can this sequence cause memory corruption and an out-of-bounds information > leak via RXRPC_RESPONSE_APPDATA? > > Looking at the remaining sendmsg code in net/rxrpc/sendmsg.c, an inverted > check incorrectly rejects user keys but accepts the keyring: This is the same complaint as was raised against an earlier patch. David