From nobody Fri Oct 3 16:47:14 2025 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 67A5913957E for ; Thu, 28 Aug 2025 03:26:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756351620; cv=none; b=LjJ0zjzacnYIj+E2uavdhtBfrkvXzxaqswwLkCbeoighsuRXvD5aygMjWm3TvQetelsS6lD04ObHJvzMobEF5iRBzBEBGO3PyouMB8LeTcMMxcnL5AFab3iPn7ZnvDgaoqEMIPCFm8AdorpVJjYJ8xJC6fMqG6tOB2fCbm7iVH8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756351620; c=relaxed/simple; bh=ftdmSlNt09FgQY4pEvWWw7yJUxA83F1tEXsoFtLyi3s=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=ffB1iHG+2vgGqIqX8e95e4FmEICXOf3teyfaSOcSDXZzrC39cA8Ww/FV+hWYKpL4uJqa/ozANjw6GnqB+y0mOKhDL4UiiksIE8Iq6AtC0vnM68YgeQhXaTetzokXKQJWKP1j6Yuwo7r+hII9eCPHyhHpDfYBUm6IL90o9tNFyRQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=yK2BkNFp; arc=none smtp.client-ip=209.85.214.201 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--cmllamas.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="yK2BkNFp" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-248d9301475so4271945ad.0 for ; Wed, 27 Aug 2025 20:26:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1756351618; x=1756956418; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=/WwDqhBFvfX8vGdZlaGfr2aX/pAs2877vUWTmC3CYPY=; b=yK2BkNFpJoBiQ1H5/AwQpYZr+rxDxxQtS1L2sgzky0AlXJ0PMNNKlSEJ8DYhf3E6GA X6M5q38TEIifI6cg/VDwjUeKWQyODHz2FaUYZILXUYaWG5OnSrhm+85XciX+fcVTwhyY +iZb662jSQU59ia7gzbhKLIpKCws8s5KCyzHXzg51rBv5cJX+Uh5vh49Vcs2If+D3WWh yNYvgPAXF7nfZeigKuM0VVqYIL5djxSKJ6NuICRTlrw5KErc+Rhl7p1mF5X5S76CDy66 g5irpUVLeqGhla1PobI2eonzoYwsnFM5i5qsiIxRiCQZQIIqv9Xh0GSMwGrpcOkciNxf pCDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756351619; x=1756956419; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=/WwDqhBFvfX8vGdZlaGfr2aX/pAs2877vUWTmC3CYPY=; b=XYhOkALRuGGE1JnxU6SCIv6lWET5xvN99GfG5q8tbS/ra8xSNVbHg9lhdPomoYLrqf wlO9kJC2S0RBSAjK+0y6kgLaJV3UECgoBRtclb8anKYEHLksU1+Gb2oVR6pts/tRBd/y MEfbL+nQeoFcL6vya0+aNYgEjoCu6I6tpzxXYaxGUIfOV7zTgudRClM24yNnL5dz7kGc o2od3Yxe0G7dHaOiHEpfBTURnOWQ+SMedZK5ZfHm7lO+pvLmd8ps4eURRi1BaQJTM2ta 1RbCgzlEDxqO6zl92SC4eMaIrd6FCUBbymYxs752MgbjI2UCTF/D+TMmwE1C5wd0ajdJ 8h+g== X-Forwarded-Encrypted: i=1; AJvYcCWI6B6LoI8vFaefurTrtadZKAPzWN3qeDU3zPU1jP9pYc0xnyEWlyJ3PKfpL1T99VXOJnjAZQDjnR4t5/E=@vger.kernel.org X-Gm-Message-State: AOJu0Ywvd1udbpblwwmOLtlOa7Mx/DwUldsUTattfDRLr55mcpwsZT7p /MKUwLHZ24hOkzEE/Odutf08ot3MX60OYrpYgUOVDhnffbyykGa7f7Q1azNjPI4NFUhyxjdztey tFqofPJRJxNffXQ== X-Google-Smtp-Source: AGHT+IFxSA9GIyNl3LjYDLq/9j+Nr4FbBkqdslTMspmmUmyNwznrDCKsEp0DmZ+NS6CY1yHpDOzTMPRVndE+uA== X-Received: from plfz1.prod.google.com ([2002:a17:902:d541:b0:248:beac:b4f1]) (user=cmllamas job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:f707:b0:235:f459:69c7 with SMTP id d9443c01a7336-2462efa8c13mr281904895ad.52.1756351618636; Wed, 27 Aug 2025 20:26:58 -0700 (PDT) Date: Thu, 28 Aug 2025 03:26:52 +0000 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 2.51.0.268.g9569e192d0-goog Message-ID: <20250828032653.521314-1-cmllamas@google.com> Subject: [PATCH] mm/mremap: fix regression in vrm->new_addr check From: Carlos Llamas To: Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pedro Falcato Cc: kernel-team@android.com, linux-kernel@vger.kernel.org, Carlos Llamas , "open list:MEMORY MAPPING" Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Commit 3215eaceca87 ("mm/mremap: refactor initial parameter sanity checks") moved the sanity check for vrm->new_addr from mremap_to() to check_mremap_params(). However, this caused a regression as vrm->new_addr is now checked even when MREMAP_FIXED and MREMAP_DONTUNMAP flags are not specified. In this case, vrm->new_addr can be garbage and create unexpected failures. Fix this by moving the new_addr check after the vrm_implies_new_addr() guard. This ensures that the new_addr is only checked when the user has specified one explicitly. Fixes: 3215eaceca87 ("mm/mremap: refactor initial parameter sanity checks") Signed-off-by: Carlos Llamas Reviewed-by: Liam R. Howlett --- mm/mremap.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index e618a706aff5..692acb0f9ea2 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1771,18 +1771,17 @@ static unsigned long check_mremap_params(struct vma= _remap_struct *vrm) * for DOS-emu "duplicate shm area" thing. But * a zero new-len is nonsensical. */ - if (!vrm->new_len) - return -EINVAL; - - /* Is the new length or address silly? */ - if (vrm->new_len > TASK_SIZE || - vrm->new_addr > TASK_SIZE - vrm->new_len) + if (!vrm->new_len || vrm->new_len > TASK_SIZE) return -EINVAL; =20 /* Remainder of checks are for cases with specific new_addr. */ if (!vrm_implies_new_addr(vrm)) return 0; =20 + /* Is the new address silly? */ + if (vrm->new_addr > TASK_SIZE - vrm->new_len) + return -EINVAL; + /* The new address must be page-aligned. */ if (offset_in_page(vrm->new_addr)) return -EINVAL; --=20 2.51.0.268.g9569e192d0-goog