From nobody Thu Dec 18 08:38:46 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 1D6AC2236E3 for ; Tue, 9 Dec 2025 22:42:02 +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=1765320124; cv=none; b=ut8eS1FTNSEqduiP3TvK40qwvg91HlSGE0Ktry/TCtD4Wq/rykX0xLYLOU7PR0Stj/3ofWRYwpifEPYpV29jYsV8kXHU45j2uhDhLkymSMVLGCwVXT1PipNWzvcg+loK+0kpu4qGGagMfCswgd0mByYOCv9tq2d9r452BStlGPo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765320124; c=relaxed/simple; bh=e+ucK585AGlMEt1FtkAGooQCIpfCO48sMtQRq4dmTYk=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=Dx7nQpS/YaegiTYfSGw013a+WTrnc7YGSkz2PDW/7jOBwLsuGvxyQHvej53xXFdIo0g4Ses4pVXB0gPWWcKgZQTfnyrypD08TVU6CA+c4xv+icYQ+RaVc4aFNEDnnrr0v3rVVKYsUXbKeVJCIhA3K36pYuWumiEqsYdRVatY0JM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=D/qXN27B; 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--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="D/qXN27B" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-29846a9efa5so109639955ad.0 for ; Tue, 09 Dec 2025 14:42:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1765320122; x=1765924922; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=ZX3tHWxGta59786KLml5QZQM76pAjUTO+0DLCyLkw/k=; b=D/qXN27Bm12MBfNMjIdVLLsbiBqmCGoUPvnKM1H6WD2pHC1pHkbXFcXEYA/gcro4xs 5ewbzf/2w02yklhgyTVag4dh6alb4cGbHRZQSK7pSC/ReMdNjtAthTEFwNX8dgu+Stts 6D3tSZypiuK6DhR5AyHBy1yo7wkTqddeCQ2xbNqOjBx8C91zDyeaBHWvL9za/Tl0yxGC 3x9ndzwYPGsGtVT8N/sRMk0Hwkzt2sszz3QQCCyMkCYVk2DdKxtWSIVqWZB6mSLzRxBW r0M1Hd3Yy6RgFNjX8m7jhLV6+OU9JEY9dKsRUpWDhPonIAtHUVo25qQt5e68gnoTdBWK heAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765320122; x=1765924922; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ZX3tHWxGta59786KLml5QZQM76pAjUTO+0DLCyLkw/k=; b=l0LI7OmPESQp6RUZe5L6ZBEj3Z1u5fjuUX2ivMjerXBs8A5Y/++CH0AFb4iJBNd3B0 paLKkj1kC5Xv+7GoJAlIk/A/BsV2oV+PZUHnrQQxR+SQ1Fc3QdsDsZFWpDxlQir9nhAI IEi9ZiS5iTfgrH5+CzYvvhVQCH1q75Nh7SEk4eZIbDPm26RhHIxrguTOMmoEYjH/X0Qw EZsrB4kuDz2nwzUceB/izkRxldqU/qCx409Ek6mEyWhQuJG2b8JqFn7bjRdvrudZkI2b eAKEdii8fbxiPd5LpTAFZHGd+XLI37RUpvMeVGD8ka2auLM6YvrJsKIVwEokPDli/J5F kN3w== X-Forwarded-Encrypted: i=1; AJvYcCViFoXyTzo4mLL+2RjRdmCTfWZdFEVNtl2ru84gkzMKJb/GpaTKshcLBI2yXegJL7KmYGo0ZOCbIaqWjc0=@vger.kernel.org X-Gm-Message-State: AOJu0YyurB32dA47KEHTZLl3VbFTWSEpe8891QRVNKZwyQC1Qt0RmmCw SZoT1jd2kIukjgP84oLXJwXDKPsUiMUxLufhr2v83uTaC/qTH4SReesmqDXzyRnA6428mamwdta ZylDGx9p9wg== X-Google-Smtp-Source: AGHT+IGuQ27qcyshFHD2sZEa+vgFWpq8UYHdpNMLlsAKuXlm2Pd8j549RB0SwIHcR3gDLFlXVf/zP9cLpFMB X-Received: from dlbcj39.prod.google.com ([2002:a05:7022:69a7:b0:119:49ca:6b90]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:2484:b0:119:e569:fb9a with SMTP id a92af1059eb24-11f29655a60mr255787c88.9.1765320122268; Tue, 09 Dec 2025 14:42:02 -0800 (PST) Date: Tue, 9 Dec 2025 14:41:58 -0800 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 2.52.0.223.gf5cc29aaa4-goog Message-ID: <20251209224158.2322551-1-irogers@google.com> Subject: [PATCH v1] netlink: Remove implicit 32-bit trunction in nla_memcmp From: Ian Rogers To: Andrew Morton , linux-kernel@vger.kernel.org Cc: Ian Rogers Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 64-bit truncation to 32-bit can result in the sign of the truncated value changing. The nla_memcmp function subtracts a 16-bit nla_len from a size_t size and so this shouldn't occur, but the code looks hazardous so change it to make the comparisons explicit and avoid a truncated subtract. Signed-off-by: Ian Rogers --- lib/nlattr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/lib/nlattr.c b/lib/nlattr.c index be9c576b6e2d..6e1c40dd11e3 100644 --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -854,12 +854,12 @@ EXPORT_SYMBOL(nla_memcpy); int nla_memcmp(const struct nlattr *nla, const void *data, size_t size) { - int d =3D nla_len(nla) - size; + u16 l =3D nla_len(nla); =20 - if (d =3D=3D 0) - d =3D memcmp(nla_data(nla), data, size); + if (l =3D=3D size) + return memcmp(nla_data(nla), data, size); =20 - return d; + return l > size ? 1 : -1; } EXPORT_SYMBOL(nla_memcmp); =20 --=20 2.52.0.223.gf5cc29aaa4-goog