Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA6093C8716; Tue, 21 Jul 2026 20:57:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784667483; cv=none; b=TOgeEuShvEloC6N85Oec9HWOf2Eh0/fJyDPifPYsdAUMEfFE8BdSxX804UBgZHxUkOMaEi/zv4VtW7PNqwQGnTeKI1GEjIwbqMM+AKnmjuE0vIkkjjVruOhudCVTvuU1vOM+dmW0kaPTyEFxUUE+rS+EDN19FGrCjnRUjVyJ6+k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784667483; c=relaxed/simple; bh=Y+RW+dBlHXOWGtCQfmfB7UqKp4pdutqwytIRd5XyAQg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jlgMv5tCQ1GupVqMEoNKLrEuMUpZIl9LGUjL6pqF0WPJK1gAXyNX8ayoYKW4bBkxHai85QsHp5ltdIia7oV2Ryqi69jAExJN88DWSVo603iNst0NVeqHrVlRWlSiAIFnXbrQlH5pDm/CvR8UQ8Mk+shMelpzPGApDNBKxh2MuKY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Zv5pE2OL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Zv5pE2OL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FA6E1F00ACF; Tue, 21 Jul 2026 20:57:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784667471; bh=gVJeKSTWpLnVWasf3BJicwE3VrPU8AQsld9bCR7YFE0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Zv5pE2OL3TDzYnJQYAV1CZeFmxPdEv8FzUvLeyLjWV0Ic4tUByuZhtBllhg44G0Pj Sy4TzChYcg0Miozd2A8VlMNGVrSmCCLwvTFgPjskWJcHcW2/enfeXm1hl/0Jj8N2kq xzyYZ08Mf9QoBAiHLA7wgqTk05K0RbP6RLhMlc44= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhan Xusheng , Thomas Gleixner Subject: [PATCH 6.6 1075/1266] posix-cpu-timers: Use u64 multiplication in update_rlimit_cpu() Date: Tue, 21 Jul 2026 17:25:12 +0200 Message-ID: <20260721152505.873556444@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhan Xusheng commit 26aff38fefb1d6cd87e22525f41cc8f1aa61b24f upstream. update_rlimit_cpu() converts the RLIMIT_CPU value to nanoseconds with u64 nsecs = rlim_new * NSEC_PER_SEC; On 32-bit kernels both rlim_new (unsigned long) and NSEC_PER_SEC (1000000000L) are 32-bit, so the multiplication is performed in unsigned long and truncated for rlim_new > 4 seconds before being widened to u64. The same file already casts to u64 for the matching computation in check_process_timers(): u64 softns = (u64)soft * NSEC_PER_SEC; As a result, the truncated value is installed into the CPUCLOCK_PROF expiry cache (nextevt), causing the process CPU timer to be programmed to fire prematurely for any RLIMIT_CPU soft limit >= 5 seconds. The actual SIGXCPU/SIGKILL decision in check_process_timers() already casts to u64 and is therefore correct, so limit enforcement is not broken; only the expiry-cache programming is wrong. Apply the same cast here so both paths convert rlim_cur identically. 64-bit kernels are unaffected. Fixes: 858cf3a8c599 ("timers/itimer: Convert internal cputime_t units to nsec") Signed-off-by: Zhan Xusheng Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260616112017.1681372-1-zhanxusheng@xiaomi.com Signed-off-by: Greg Kroah-Hartman --- kernel/time/posix-cpu-timers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -41,7 +41,7 @@ void posix_cputimers_group_init(struct p */ int update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) { - u64 nsecs = rlim_new * NSEC_PER_SEC; + u64 nsecs = (u64)rlim_new * NSEC_PER_SEC; unsigned long irq_fl; if (!lock_task_sighand(task, &irq_fl))