From nobody Mon Jun 15 13:56:24 2026 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (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 127461990C7 for ; Fri, 10 Apr 2026 12:45:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775825140; cv=none; b=rv8vDvA9shOXx8+6o/9bfqPDvwAf7FC/M3AuKseSNvTrlsj4lIf4fW94rywH6mWjwRDNnfmyEG7sbPT9BkT1XhEoOf2rKp2PQeZHyppH/Ty2ljjqA5xzg+k0fTB6FVRJXtRdgUReiORHRNvLKIu3kXaRuyx/q9G99DWiZhBy42A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775825140; c=relaxed/simple; bh=QHiukfKSmwMd57SgXEaDANZ0GnMRsME8FwRdtZB9Mtc=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=VG9m6d3vXa5etJKkOa8H+Svqn7Yjf8Z3yUHFceEuN0ItTBC6GzRiXW6ULj7ArRBFbSaniW1EiQzoEDW7Tr1HS1HpJR7iePy3vA9zBIOAyTg9Y1Wn9PPoKOqGOixrsgcgnnc8boa4IXMExhNi4Jsz3DyVtl/9265C/wNJQ0G1fRg= 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=GZLqt15T; arc=none smtp.client-ip=209.85.128.74 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="GZLqt15T" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-488d9e1e61aso3359005e9.0 for ; Fri, 10 Apr 2026 05:45:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1775825137; x=1776429937; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=apY7Ejl8X5JBwAsC8h7VHQdCvb1Zq/PpjmokFJg+xQw=; b=GZLqt15T+z2W8h9fqW4QmSCLGS9Ja1PnIeZub+3U3fgkVyirr0y5WxbXWhDyg92EBX A7/IybLZNR6CO6lo14AXj62vI8H/5vqIFjqsSWdNFXPuvQPJ87dFgT7Tg/MINJO/T7EP WeoiUj6Xp2jc2J5B1EpxPDwjy7vI/entKwLKtwN8o+LQJWwckErXZf70kDyEI1A1jj52 Uk+H2tN2kyoZvKLrPdZyZvV9RjTnnuzwXN25w25BhfFDN8pELgg35wLgRqzozMOJ8Eaw dwQeMUn71il+mWG6Tx8tPmeCCCvpZ4CCKMRbT/qSTXbYXWjssPps8rnbP5dOLp8sNSKg nt2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775825137; x=1776429937; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=apY7Ejl8X5JBwAsC8h7VHQdCvb1Zq/PpjmokFJg+xQw=; b=eDDa0Axqu0nA8glS9of1bnZen3m0TuJ5Mt/31FfVZKUtH0H8dbKnBh5xkjNBCTjR6h 4eoZ/ceNkJcUBjPFY1kAsmvoPV5y+WMpGmA2sJ6a8kDlH0QuZt6SLy4S98wkGqx9Lqb9 P/OAi2dk/hmC3JXPrtK93PPu/fFCAvKVnpa616qEYXo3jRaMiTVLDxjGB8ouR8xyFprY WSQRwGF0bvdkRNwLjy/yUOWLyKWYlNcEYMFXgNmKbgtLIyWP9daA5fPIo+EEhULmXX4C I38Q/nhEEklPxylv/TWtkX3KN9SUN1LAgOwMoPr/PH/53S7KY9TfAe3rEYwwsL7fEQF2 /hwA== X-Forwarded-Encrypted: i=1; AJvYcCUE0d0NgRJ5Kg/OgdRHCfY4exij7kaY4qFEGo6eZ+3fczsx5L2KwT4xg28kzKQKMBcVM6aYMjw1xbAGaLo=@vger.kernel.org X-Gm-Message-State: AOJu0YwDpIqxWoW7mH6eaHh6YIePwfaue7ZmukT8ufEh/I0xtNtsNcKW m6ekTlU/r87a5HXAJPbNRX7WH3n5nfBjZqyjDgh669I7tTIhd9vkUlqRBEcJfrqnkrObucXFSIw mgXo8VQlGfa5KFeMGz6TAlQ== X-Received: from wmoo3.prod.google.com ([2002:a05:600d:103:b0:480:6b05:6b94]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:45ce:b0:488:a8f0:35bd with SMTP id 5b1f17b1804b1-488d67df745mr38438805e9.8.1775825137170; Fri, 10 Apr 2026 05:45:37 -0700 (PDT) Date: Fri, 10 Apr 2026 13:45:27 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog Message-ID: <20260410124527.3563970-1-vdonnefort@google.com> Subject: [PATCH] ring-buffer: Prevent off-by-one array access in ring_buffer_desc_page() From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org Cc: kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort , Dan Carpenter Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As pointed out by Smatch, the ring-buffer descriptor array page_va is counted by nr_page_va, but the accessor ring_buffer_desc_page() allows access off by one. Currently, this does not cause problems, as the page ID always comes from a trusted source. Nonetheless, ensure robustness and fix the accessor. While at it, make the page_id unsigned. Reported-by: Dan Carpenter Signed-off-by: Vincent Donnefort ---=20 Currently based on kvmarm/next. diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 96e0d80d492b..2c77020e7aac 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2238,9 +2238,9 @@ static struct ring_buffer_desc *ring_buffer_desc(stru= ct trace_buffer_desc *trace return NULL; } =20 -static void *ring_buffer_desc_page(struct ring_buffer_desc *desc, int page= _id) +static void *ring_buffer_desc_page(struct ring_buffer_desc *desc, unsigned= int page_id) { - return page_id > desc->nr_page_va ? NULL : (void *)desc->page_va[page_id]; + return page_id >=3D desc->nr_page_va ? NULL : (void *)desc->page_va[page_= id]; } =20 static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, base-commit: 94b4ae79ebb42a8a6f2124b4d4b033b15a98e4f9 --=20 2.53.0.1213.gd9a14994de-goog