From nobody Fri Dec 19 12:28:39 2025 Received: from mail-pg1-f176.google.com (mail-pg1-f176.google.com [209.85.215.176]) (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 4E08B1DA24 for ; Wed, 20 Dec 2023 05:29:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KGrmfskl" Received: by mail-pg1-f176.google.com with SMTP id 41be03b00d2f7-53fa455cd94so2158769a12.2 for ; Tue, 19 Dec 2023 21:29:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703050150; x=1703654950; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=bEWrGakqE+F1LdpSKKHnuv1LFOcw6TlFqunjfDsouyQ=; b=KGrmfskl0YM0zuBhYp8euVo25ScmOjugirBHRd8rVjwdR/L2qt8xtpPM/+t6QjRPeX BEmMS8vyjPiW2H0gk5VEGh1DboY7wyz4W9JdkDzpSh7Nm+HZdLNztlo7JLu6cHREFD43 r1iyeI4ZI/4q/biQrBM+nrHtyIUfpRYLTLmTw0rbpN7pxZwvphtKdpw+fS4ucQ+lVqoS DPp2kjmttIqmnT0aiVY35PVnOW5BxulXXSKrVW0/mAu7sdrPNcq/Cul57UgsGF1+Mx+d csow3QlTHzfnmrKBN5JsqCq+QqNR85YRTo0/pY4EfHNJS4GRh4hrzB/Lmw+UhPFOZzcZ 3CEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703050150; x=1703654950; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=bEWrGakqE+F1LdpSKKHnuv1LFOcw6TlFqunjfDsouyQ=; b=kyGZu0LBrwqIoZUkuRv9PCsmDikTbSztushxWdVkG43AzHp+1CPYczZYlFipCUa8kO cV+fmxPXkAvO0nIa6kK0+6FYcP4AfmTVbJbYsV4VYJPpxLQ3dJtmDB7tvh9YA8gna6Sq c5+H4qSQBfEPHd/qP1p1mjS3gtVyoouoZejAePW3/2pWkqNFR5ge47aj3UL3upVSA7l5 tK/pIWBTaHYI3IOl/8q1g8J6XrVXtaG/qxd0/4o8uQhli9rSDiXziY5ay0X1ty+tMrCG 9LDGEFcxtaVZafP4nqiS8k9JMbDFpQl9KIfU50yauVozyDV9nfMTr0F9Ko4vnOqN3fp6 UOzA== X-Gm-Message-State: AOJu0YyfUzUB5tWlHeOUYvWYK7E6PXuqTlKoD1n9+xMko9OmgbnCU9p2 2o3ckVz6BlFe7IW/aJ6WDriMEDrFrqi1L76XKy4= X-Google-Smtp-Source: AGHT+IEqjZJTRgn3/S6IXYZ/iWhcmRd+yjH2Er7v44/flHcMZBD2655sBYvpQalpuxIcXUCaFEe1/w== X-Received: by 2002:a17:90b:4b47:b0:28b:cc2f:4e02 with SMTP id mi7-20020a17090b4b4700b0028bcc2f4e02mr573114pjb.20.1703050150531; Tue, 19 Dec 2023 21:29:10 -0800 (PST) Received: from localhost ([101.224.17.173]) by smtp.gmail.com with ESMTPSA id h17-20020a17090adb9100b0028bd70dd5fesm333413pjv.12.2023.12.19.21.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Dec 2023 21:29:10 -0800 (PST) From: "jiajun.xie" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, jiajun.xie.sh@gmail.com Subject: [PATCH v1] mm: fix unmap_mapping_range high bits shift bug Date: Wed, 20 Dec 2023 13:28:39 +0800 Message-Id: <20231220052839.26970-1-jiajun.xie.sh@gmail.com> X-Mailer: git-send-email 2.35.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jiajun Xie The bug happens when highest bit of holebegin is 1, suppose holebign is 0x8000000111111000, after shift, hba would be 0xfff8000000111111, then vma_interval_tree_foreach would look it up fail or leads to the wrong result. error call seq e.g.: - mmap(..., offset=3D0x8000000111111000) |- syscall(mmap, ... unsigned long, off): |- ksys_mmap_pgoff( ... , off >> PAGE_SHIFT); here pgoff is correctly shifted to 0x8000000111111, but pass 0x8000000111111000 as holebegin to unmap would then cause terrible result, as shown below: - unmap_mapping_range(..., loff_t const holebegin) |- pgoff_t hba =3D holebegin >> PAGE_SHIFT; /* hba =3D 0xfff8000000111111 unexpectedly */ turn holebegin to be unsigned first would fix the bug. Signed-off-by: Jiajun Xie --- mm/memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 5c757fba8..6e0712d06 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3624,8 +3624,8 @@ EXPORT_SYMBOL_GPL(unmap_mapping_pages); void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows) { - pgoff_t hba =3D holebegin >> PAGE_SHIFT; - pgoff_t hlen =3D (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; + pgoff_t hba =3D (pgoff_t)(holebegin) >> PAGE_SHIFT; + pgoff_t hlen =3D ((pgoff_t)(holelen) + PAGE_SIZE - 1) >> PAGE_SHIFT; =20 /* Check for overflow. */ if (sizeof(holelen) > sizeof(hlen)) { --=20 2.34.1