From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D063147DD71 for ; Wed, 5 Aug 2026 15:32:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785943963; cv=none; b=ox1fJdVEED30xbMSSCVANwb0nzSmdHnphMGYbwx9/KiMHXA/4LJvum6mT8JWuK6LDeCfdsB9tibojhIVhoZJa+pUy0YsHvLXXEmrirzAv42/W5KvuRMbbJsOhGqGd4gB7jl2mv2UUphQBA7luAtmQQEeeji9gUMMd7+berSN3BE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785943963; c=relaxed/simple; bh=fSfHKUXXjeuaF5GoHZqzt3ghM/ntROBEcVxwVLLKf5c=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=U+RLXfUB/4C8H/DgmfYJF4nQTXQviAj8Hsb542jbVPrIxQkbHduoQSVx/Y92VkEt6MYW6Qctdbbg0JYu1iVd1UNuVl7KKqoilh6bsOA1EUvKuKAaKxM1OwX1ED3vYdxKySGM0XcAL9NgQzm5YjXafch1pXJ3xG0MjEelKltdvpE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=stizqqRa; arc=none smtp.client-ip=209.85.128.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="stizqqRa" Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-496b61bd846so8873125e9.2 for ; Wed, 05 Aug 2026 08:32:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1785943956; x=1786548756; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=dURYyTAr3xD5Ug+KUce+nub8IT6QTcigszEQZYZJDrw=; b=stizqqRanQgIpndQuGOLsWECD1eUKSphGBcuRy9HaX7RvLdQAeBkQTPHvabUKA8hfM 9H5FlYe9l2D+Bvc61C8ae0/JTEc9i0P73nXSZJLfcYcaUZkVoVOH+kHnEiqI0FKojpUM jnD2zGqeC9f35TdYO4ttmecm4dg7al1bpIavSfuoDesmWtbxCYY2ih6M/E3R13u5mJBi HSqq2X8Bth7811djhAb17gR01dmYkJhdfeBBPYAFIzq9Ge+ogTeAgcQl50qbjHKA3ptz LcuV5JohOUXogHZ2UZuLpvHTIMSsGtTq2/GL9cdWuPBJvn0XpWMNaUcs9gZJFFKwezCR AOFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785943956; x=1786548756; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=dURYyTAr3xD5Ug+KUce+nub8IT6QTcigszEQZYZJDrw=; b=cPLpoe1rtH3xPcuDr52xmsZkY+kx7Ij6KnXAGqPzs4LfPjb/bl5lftZ4sWl2C+yosk OH9Qs5v3pN7vb4n8FYN+j0xj5RNQ+UuKc4K5Pqrnn+jbhVaKC8wt6bL3xeEyU0Jv24wR 4juHXN8JHbQOGULR8PPxfOm3WIjscQY3Y45b3aPHW9H7sVwxk9h/EoZ2OPTwfLd0b3Wa 37H2RztvuLJVggmg5rvu9wnYB/bIIQQmtcV0TXCMMPKyaKSC7WJd8OZDxV4Dz4AuXmvw 6alq739QST6u1oHS4q26Xpf/NIpQZWPF7KjJR9iYJ4GULfvLl4S+iCDVTj2PfpxTXK18 tYxw== X-Forwarded-Encrypted: i=1; AHgh+RpSAJVFmPY1GUa0pyWbwaJDF4IxiOEYAz7piCkATnnAHBWDjA0jxzTTbeHgPsLLUFmnud9uj4MY0QuHcL+wtLdNdyo=@vger.kernel.org X-Gm-Message-State: AOJu0YwFQUlMM+eUptsr39urXmAmyXXYCvqohD9NREGGy30ad+kkzr2f ExYWzYlXkN7KFYbXHzGsU8MpVyHYmPbsWrVqchpWSUN5PGqzGLd7XFyMBZ0A3wziasfjoIt1M0S ZOc9gGO+1lB0E6oNZaQBlrA== X-Received: from wmby14.prod.google.com ([2002:a05:600c:c04e:b0:495:3c12:fb52]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:4595:b0:498:952:e276 with SMTP id 5b1f17b1804b1-4994e79e377mr64342435e9.8.1785943955841; Wed, 05 Aug 2026 08:32:35 -0700 (PDT) Date: Wed, 5 Aug 2026 16:32:24 +0100 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.571.g244d577d93-goog Message-ID: <20260805153225.2096152-1-vdonnefort@google.com> Subject: [PATCH] ring-buffer: Prevent subbuf order change when resizing is disabled From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort , syzbot+e0cc44465d6bae735679@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Because ring_buffer_subbuf_order_set() frees buffer pages, we can't allow it when risizing is disabled. A non-consuming reader is at risk of use-after-free (rb_advance_iter()). Return -EBUSY on resize_disabled, matching ring_buffer_resize() behaviour. Fixes: f9b94daa542a ("ring-buffer: Set new size of the ring buffer sub page") Reported-by: syzbot+e0cc44465d6bae735679@syzkaller.appspotmail.com Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8e2485bb3aa8..414bca2121a7 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7358,7 +7358,7 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) cpu_buffer = buffer->buffers[cpu]; - if (cpu_buffer->mapped) { + if (atomic_read(&cpu_buffer->resize_disabled)) { err = -EBUSY; goto error; } base-commit: 075b74841bd0065a3bda3440873c747938e69b68 -- 2.55.0.571.g244d577d93-goog