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Mon, 13 Jul 2026 17:38:21 -0700 (PDT) Sender: Mark Harris From: Mark Harris To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: Alexandre Ghiti , Mark Harris , Nam Cao , Michael Ellerman , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] riscv: hwprobe: Avoid uninitialized read in hwprobe_get_cpus() Date: Mon, 13 Jul 2026 17:30:56 -0700 Message-ID: <20260714003056.73707-1-mark.hsj@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When cpusetsize < cpumask_size(), hwprobe_get_cpus() did not fully initialize its copy of the cpu mask, which could cause non-deterministic results from the riscv_hwprobe syscall on a system with more than 8 CPUs when the supplied cpu mask is empty. Address this by fully initializing the cpu mask. Fixes: e178bf146e4b ("RISC-V: hwprobe: Introduce which-cpus flag") Signed-off-by: Mark Harris Reviewed-by: Nam Cao Reviewed-by: Michael Ellerman --- v2: Add Fixes: and Reviewed-by: tags arch/riscv/kernel/sys_hwprobe.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c index 1659d31fd288..caf6762427c8 100644 --- a/arch/riscv/kernel/sys_hwprobe.c +++ b/arch/riscv/kernel/sys_hwprobe.c @@ -450,6 +450,7 @@ static int hwprobe_get_cpus(struct riscv_hwprobe __user *pairs, if (cpusetsize > cpumask_size()) cpusetsize = cpumask_size(); + cpumask_clear(&cpus); ret = copy_from_user(&cpus, cpus_user, cpusetsize); if (ret) return -EFAULT; -- 2.55.0