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Fri, 17 Jul 2026 18:33:27 -0700 (PDT) From: "Cen Zhang (Microsoft)" To: include@grrlz.net Cc: AutonomousCodeSecurity@microsoft.com, avagin@gmail.com, blbllhy@gmail.com, brauner@kernel.org, jack@suse.cz, kys@microsoft.com, linux-kernel@vger.kernel.org, mjguzik@gmail.com, oleg@redhat.com, ptikhomirov@virtuozzo.com, tgopinath@linux.microsoft.com Subject: Re: [PATCH] pid: fix cad_pid use-after-free race in proc_do_cad_pid() Date: Fri, 17 Jul 2026 21:33:25 -0400 Message-ID: <20260718013325.5651-1-blbllhy@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Thanks both for the review. One impact clarification: this is not init-namespace-root-only. The sysctl is mode 0600, but access is checked against the owning user namespace, so an unprivileged user can reach it via userns + pidns + a proc mount. The demonstrated impact is a KASAN UAF. On non-debug builds the proc_do_cad_pid() read path likely only returns a stale pid value unless the freed pid object is reused in a very tight window. I'll send a v2 series as suggested: patch 1 deinlines kill_cad_pid() without functional changes, and patch 2 contains the updated fix.