From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F415C3526C for ; Sat, 19 Dec 2020 17:06:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DAE223A9F for ; Sat, 19 Dec 2020 17:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727106AbgLSRFv (ORCPT ); Sat, 19 Dec 2020 12:05:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726985AbgLSRFv (ORCPT ); Sat, 19 Dec 2020 12:05:51 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BBDAC0613CF for ; Sat, 19 Dec 2020 09:05:11 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id k7so8032471ybm.13 for ; Sat, 19 Dec 2020 09:05:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:cc; bh=vRLuXOIA8ra1QfYJtJa6fHDyAv5QMA5uNL7Qfw/l2xY=; b=HWimkrBOC8ZIriK9HG74tC08/J66mjh16qNL2u/hX9z4DtBTOI3PLS/VmIBgtHgm9+ oYOWiJCYs+V4J7ubKHvfBqo71hOpbfn4DiycoDKwTvIMnHjIiFmojmbOqYoVM348ILAa r0rE4NQvpACZFo/ZvJbqEazXPskml7zeyzemvEMNIsFtA3bzK0Ybs+BMzf/DksqTnGnF jwIf8UEnZ1A0sOhQTBhAg48XKATfgXZGk54r9+/IqMTjQjJcvSKPFHgZuYUKteGas+7x gxdKbWiHvF+h76pCj18NzcKdblvSJq0+cgFGNZSvusbXw5aQbjQyp3madF2aEfaFT8rX v1Dg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :cc; bh=vRLuXOIA8ra1QfYJtJa6fHDyAv5QMA5uNL7Qfw/l2xY=; b=fM/YaDBtYwzmuCIAbT4wW1nz50C+2ErcQ/DiG2H0+7x+O8+gh6cLYb+PoulHtjNZ/w CIhSk3nW1br8gRZap/vXqI90gfgIaQ/lRqn/UxzkQ76XuamcMmQ0emBQZFjcnUCwUGJk nBv+IbWCKk5Kpziomp0VQKgDmj19Zvoa83KyLT6WQ8W2n5Cy/IUKOmWeC/9DUGrZ9X7X u6nSKnH3q2bPUk9Qfs3EmgKVNqbFZVjiNvIqaz07OEFVBLUL217iK2uVSbC4aq+x6sYH h0BsJdP9GjRGKxd3T/FklWdF2S455F/HED5+RWnO2AN6mGsC7kbIsKfSQU2+zVsok2rh D/AA== X-Gm-Message-State: AOAM533K7O+jKLq2gMXybU1EXwc9HcsBu7rj60Q5YqO+yr2W1X0uN88I vwMZzgNwZHlOMaf4CzRxs5XdRJIsRfaLojDOQw== X-Google-Smtp-Source: ABdhPJynjoV9VkSkhhIshxUKIFINAPf+sn8pGQ14p/7YjLEdfYWCJUzeZOOgVOwmhgKi8bRkAoffv0ZRs5VUt/0JYg== Sender: "kaleshsingh via sendgmr" X-Received: from kaleshsingh.c.googlers.com ([fda3:e722:ac3:10:14:4d90:c0a8:2145]) (user=kaleshsingh job=sendgmr) by 2002:a5b:812:: with SMTP id x18mr13542220ybp.334.1608397510135; Sat, 19 Dec 2020 09:05:10 -0800 (PST) Date: Sat, 19 Dec 2020 17:04:33 +0000 Message-Id: <20201219170433.2418867-1-kaleshsingh@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.29.2.729.g45daf8777d-goog Subject: [PATCH] mm: mremap - Fix extent calculation From: Kalesh Singh Cc: surenb@google.com, minchan@kernel.org, joelaf@google.com, lokeshgidra@google.com, kaleshsingh@google.com, kernel-team@android.com, linux@roeck-us.net, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When `next < old_addr`, `next - old_addr` arithmetic underflows causing `extent` to be incorrect. Make `extent` the smaller of `next - old_addr` or `old_end - old_addr`. Reported-by: Guenter Roeck Signed-off-by: Kalesh Singh --- mm/mremap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/mremap.c b/mm/mremap.c index c5590afe7165..f554320281cc 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -358,7 +358,9 @@ static unsigned long get_extent(enum pgt_entry entry, unsigned long old_addr, next = (old_addr + size) & mask; /* even if next overflowed, extent below will be ok */ - extent = (next > old_end) ? old_end - old_addr : next - old_addr; + extent = next - old_addr; + if (extent > old_end - old_addr) + extent = old_end - old_addr; next = (new_addr + size) & mask; if (extent > next - new_addr) extent = next - new_addr; -- 2.29.2.729.g45daf8777d-goog