From nobody Thu Sep 24 21:19:57 2026 Received: from fhigh-a4-smtp.messagingengine.com (fhigh-a4-smtp.messagingengine.com [103.168.172.155]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CF1B620D4F0; Sun, 20 Sep 2026 16:46:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.155 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789922794; cv=none; b=nsYzRU0N7AY0hMbkqn96gJX2Hw2kZ6pNn2EbivVpQY/tqis0wZeZFmdLlRLoByngtt8V0LQpSufLbAio2iRoVqjY6H8xWXekgcQf47YMuAf5MpMo1lErqd+HPqhT96g63bNbtM22bF4rmcLkfYpU8W81toN8MMClF5S/AWDPplI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789922794; c=relaxed/simple; bh=cwbVmosMdNzOmzxOocnfv58pq8OrH1rWo/xqEunwrSk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=kyCskStWuAIfQGRsv0/LG0yC8hD4Jyq0yDDTmz3qdxLTRHKXmTsfSRz4nHIxii0jNWqPHCG7UdS163GFOoSUGaoPZvIKzRmv2EpFKzS2Hph0Omfd4mT2y3bCabCVyYlRiLoXhReVH5xhbjFZBClH/xKA/LmDYJ4I68aLS+HlJT4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=jannau.net; spf=pass smtp.mailfrom=jannau.net; dkim=pass (2048-bit key) header.d=jannau.net header.i=@jannau.net header.b=UC0o842M; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=X9wF+5TW; arc=none smtp.client-ip=103.168.172.155 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=jannau.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=jannau.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=jannau.net header.i=@jannau.net header.b="UC0o842M"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="X9wF+5TW" Received: from phl-compute-08.internal (phl-compute-08.internal [10.202.2.48]) by mailfhigh.phl.internal (Postfix) with ESMTP id 0D3A814000F9; Sun, 20 Sep 2026 12:46:32 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-08.internal (MEProxy); Sun, 20 Sep 2026 12:46:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jannau.net; h=cc :cc:content-transfer-encoding:content-type:content-type:date :date:from:from:in-reply-to:message-id:mime-version:reply-to :subject:subject:to:to; s=fm3; t=1789922792; x=1790009192; bh=o7 O5QEo6XJgjk53ya7NUf6tNPrS075bjtNXyyBAspCo=; b=UC0o842MA0YITiWKCK Fwaw18hMDBypgmfXVSHZEu/HVCtVZVj3OB95BmpD6YxhQzQWzbqV+9ruhyAZMloD Wv3XP5tLRBwX8GjmX5fbhaA+8Yj4tNY3Tb3AafEaaXShQHaETYBV+ld4Vs7IjTW/ UWSz/h40eVCwY7ZlEWxvbx4w33gDz2ofw9VpoEwprWs1d4imAMTIvL1jtyd+HpKa kSpgaIetRtnQpt9L5tytq36bWiy6oSD7aLrNAaAhRrcb0AnqSmlR1G3p/+BT0ngO ++cR0B6Z9+qQ2Rrgi9Nfwto1W01nr8VHQ3aXWTaK+mvXWwNQjH+k5UIu2VPEJ79e li4A== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:content-type:date:date:feedback-id:feedback-id :from:from:in-reply-to:message-id:mime-version:reply-to:subject :subject:to:to:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; t=1789922792; x=1790009192; bh=o7O5QEo6XJgjk53ya7NUf6tNPrS0 75bjtNXyyBAspCo=; b=X9wF+5TWFulMzcXTJaZKvOwFHyAG7LgudcSfY1NsSEgX sDCqiJ4LMvVrCYlJFhuEyEMiLwA12s5Aq8e43wn7isViCsZd4Iij3GdtT1lr+0b5 IUrWuAmK7A4KRIS/LGQsszO+0O2m37Mtlgqst2qfwuF2hUzUFn1ze3t50vPq0Lt8 /HZGe72Io83IvTe+/pUHXUsbUPsGCZn2JFhpaKApRf67AB7MRLNDvhE1KMsDg/hw iXaaByvWbyMY5/ZUg5C/LJRX/bdu1OI7Zfjuq81X0z0ZxLibeDH4TaPhTuL2UNRa 7Fm/QVwyjBnOc1AXt3AkD0ZjNcsM8mQVDMtBmmsPKA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGXrODxUxlELcG4cfWRvMFXzpEv1fqsz8KQ1fkVI/BTINQBKMhTazAL1zbP+nt2n2 TrKt8P07/7Y7YhCdHKf4eIpiqZqnpiRf2y4QlyEXO8EfVNDclckZVWJHSWwZ+rhIANkzQo Qm9VGY8rIyfi5vHBM7fCiuj8EuQiQAxqi5Of2TRBPxgan3dCykQaYbBFaFUnl5Jazt9lYV /DriiElB2CbeBghZyjsue7LxrjTMwsQ0e25bQHY5g5FquCiKV8ozdcCVEBBQLGEn+dw8EG /Hgm57Pkuzs+TQkMi80khBm2kI5YUzMgVm7x+16D/0X+Fe4AFq0yFw3mhxqC2RqImi47GE LLlJw9GwpAHCtD8rbxM8T77pF3qHeWEfEIB+xV0zaoSEIC5DqDL3iLt0PJdPOa7Ayd82EM j7r3mG14IQa8BrAxVzBYUgPGeKWcRCqtpxPGVGUH+o5S+Z5itMc4x8dlRbNNDRCNvY1ri0 2W7KF8dvUwK2ypSUfyv09QZe92U/A8JOVyO1PV10JPA6RKgrLvCdPJpqZ8HvAaV+dMz/GP aq25aNc700wXzQShGlco2eiriue7jnbCoAPJXVFecG05UKFbemy/tz2TR8p50P+/yEuIh0 0/WTkEGCUIkR5SVZVVkoQ6+UdMEfy5M6mIBv7W0T0JT90e5n3FZWJSf/Q1XA X-ME-Proxy: Feedback-ID: i47b949f6:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 20 Sep 2026 12:46:30 -0400 (EDT) From: Janne Grunau Date: Sun, 20 Sep 2026 18:46:19 +0200 Subject: [PATCH v2] nvmem: core: Fix OOB read for bit offsets of more than one byte Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260920-nvmem-read-oob-bit-offset-v2-1-feeb7b672059@jannau.net> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/42NQQ7CIBBFr9KwdgxDY2NdeQ/TBYXBjknBABJNw 93FnsDle8l/fxOJIlMSl24TkQonDr6BOnTCLNrfCdg2Fkqqkxwlgi8rrRBJWwhhhpkzBOcSZbA GjXL9qN1gRNs/Izl+7+3b1HjhlEP87FcFf/afakFAmAeUhGdjbW+uD+29fh09ZTHVWr++FJFsw wAAAA== X-Change-ID: 20250901-nvmem-read-oob-bit-offset-dc1c2f39af6c To: Srinivas Kandagatla , Dmitry Baryshkov , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Dmitry Sinyavin , Janne Grunau X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2044; i=j@jannau.net; h=from:subject:message-id; bh=cwbVmosMdNzOmzxOocnfv58pq8OrH1rWo/xqEunwrSk=; b=owGbwMvMwCW2UNrmdq9+ahrjabUkhqwNvLfnOoQxSc0o/BNr3mU4LUzi/v6s2U7P7q/6tIrzd EuznMeajoksDGJcDJZiiixJ2i87GFbXKMbUPgiDmcPKBDJEWqSBAQhYGPhyE/NKjXSM9Ey1DfUM jXSMdYwYuDgFYKq1shkZJqZy72MxmOVTyGsddKak2SuPm69BxelGRM7VoK+M1ttmMTI0cXs3xIX k8gWFZUxav2P3oSmL/v85N/uTum/U/Ylcm1mYAQ== X-Developer-Key: i=j@jannau.net; a=openpgp; fpr=8B336A6BE4E5695E89B8532B81E806F586338419 When the bit offset is BITS_PER_BYTE or larger the read position is advanced by `bytes_offset`. This is not taken into account in the per-byte read loop which still reads `cell->bytes` resulting in an out of bounds read of `bytes_offset` bytes. The information read OOB does not leak directly as the erroneously read bits are cleared. Detected by KASAN while looking for a use-after-free in simplefb.c. Cc: stable@vger.kernel.org Fixes: 7a06ef751077 ("nvmem: core: fix bit offsets of more than one byte") Tested-by: Dmitry Sinyavin Signed-off-by: Janne Grunau --- Changes in v2: - added "Cc: stable@..." - added Dmitry Sinyavin's Tested-by: - use 12 char SHA1 in Fixes: tag - Link to v1: https://lore.kernel.org/r/20250901-nvmem-read-oob-bit-offset-= v1-1-b610e18cdd3c@jannau.net To: Srinivas Kandagatla To: Greg Kroah-Hartman To: Dmitry Baryshkov Cc: linux-kernel@vger.kernel.org --- drivers/nvmem/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 0556d140170a..b4e5069d9e38 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -1598,12 +1598,14 @@ static void nvmem_shift_read_buffer_in_place(struct= nvmem_cell_entry *cell, void *p =3D *b++ >> bit_offset; =20 /* setup rest of the bytes if any */ - for (i =3D 1; i < cell->bytes; i++) { + for (i =3D 1; i < (cell->bytes - bytes_offset); i++) { /* Get bits from next byte and shift them towards msb */ *p++ |=3D *b << (BITS_PER_BYTE - bit_offset); =20 *p =3D *b++ >> bit_offset; } + /* point to end of the buffer unused bits will be cleared */ + p =3D buf + cell->bytes - 1; } else if (p !=3D b) { memmove(p, b, cell->bytes - bytes_offset); p +=3D cell->bytes - 1; --- base-commit: cee9395acd8043be0644b25c34bfa86623f2b935 change-id: 20250901-nvmem-read-oob-bit-offset-dc1c2f39af6c Best regards, -- =20 Janne Grunau