From nobody Sat Jul 25 02:43:53 2026 Received: from cstnet.cn (smtp25.cstnet.cn [159.226.251.25]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A4564071CA; Mon, 20 Jul 2026 11:56:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.25 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784548590; cv=none; b=PdcmBspG4HOjh+zFvWOx3SYBfHgpPtyPSXCcegVQbhpyTBCw13/8Z6n9+fPGfSmBpMIPhaUyazYaNd5czjySwslpOg1v9krxYCz5WKcmlHET9kzLT6Avrtpe130l4tCTPVS4g962JQ5lQrVeDS0eyXOmUV815yH4h+0+Y8Yhgmg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784548590; c=relaxed/simple; bh=MWtnJZ1NiFv1kc36EpYZBpO+qly1+Vg1gFwrxTtEOC4=; h=From:To:Cc:Subject:Date:Message-ID:Content-Type:MIME-Version; b=VUqKK96P70BpWPRq74RVNQx11SPsuuVgKbcVJoIuDdKX3ecEpVXWOs79V3rAGbuHzHzkNdlNBCJ059ozKA35ekmWCQDKHrY7Rrp8zFvRlAZCx2nMIeFsdnn6o0s4tBfVM7MKIinbss330TycUSMewUjshkmpX2Q9DuNNE/hPI+w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.25 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from localhost.localdomain (unknown [111.196.245.140]) by APP-05 (Coremail) with SMTP id zQCowAB35T_oDF5qodaIAA--.63033S2; Mon, 20 Jul 2026 19:56:24 +0800 (CST) From: Pengpeng Hou To: Tyler Hicks Cc: Michael Halcrow , ecryptfs@vger.kernel.org, linux-kernel@vger.kernel.org, Pengpeng Hou Subject: [PATCH v2] eCryptfs: bound the packet-length peek to the user buffer Date: Mon, 20 Jul 2026 19:56:24 +0800 Message-ID: <20260720115624.5426-1-pengpeng@iscas.ac.cn> X-Mailer: git-send-email 2.50.1 Content-Type: text/plain; charset="utf-8" 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 X-CM-TRANSID: zQCowAB35T_oDF5qodaIAA--.63033S2 X-Coremail-Antispam: 1UD129KBjvJXoW7Aw48urWxJw1fGr15urWfKrg_yoW8Cr4DpF 1Fka43Xwn8tw4UCF4UC3Z5XF4UWa9xJw18GrZ7Zw10kwsrZFyfKFWa93yqga4rCFW8J34U trZ8KrWFkF1ayaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkC14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUtVWrXwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY1x0262kKe7AKxVWU AVWUtwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14 v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkG c2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7CjxVAFwI 0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVW8JVWx JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfU8-B_UU UUU X-CM-SenderInfo: pshqw1xhqjqxpvfd2hldfou0/ ecryptfs_miscdev_write() accepts the minimum one-byte packet-length encoding, but always copies the maximum two-byte encoding from userspace before parsing it. A six-byte message therefore reads one byte beyond the submitted user buffer. Zero-initialize the peek buffer and copy only the packet-length bytes present. The existing exact packet-size check still rejects truncated two-byte encodings after the parser determines their encoded length. Fixes: 8bf2debd5f7b ("eCryptfs: introduce device handle for userspace daemo= n communications") Signed-off-by: Pengpeng Hou --- Changes since v1: https://lore.kernel.org/all/20260715083702.29471-1-pengpe= ng@iscas.ac.cn/ - drop the redundant explicit two-byte encoding check - retain only the bounded pre-parse copy identified by the reviewer - rebase onto v7.2-rc4 fs/ecryptfs/miscdev.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c index 5a7d08149922..68804399a5df 100644 --- a/fs/ecryptfs/miscdev.c +++ b/fs/ecryptfs/miscdev.c @@ -360,7 +360,7 @@ ecryptfs_miscdev_write(struct file *file, const char __= user *buf, u32 seq; size_t packet_size, packet_size_length; char *data; - unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE]; + unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE] =3D { }; ssize_t rc; =20 if (count =3D=3D 0) { @@ -376,7 +376,8 @@ ecryptfs_miscdev_write(struct file *file, const char __= user *buf, } =20 if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET], - sizeof(packet_size_peek))) { + min_t(size_t, count - PKT_LEN_OFFSET, + sizeof(packet_size_peek)))) { printk(KERN_WARNING "%s: Error while inspecting packet size\n", __func__); return -EFAULT;