From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E7AF2480DCF; Tue, 25 Aug 2026 13:35:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787664938; cv=none; b=NO3WDw4CXgZfoM/rqfeqECm9KkSJRQ+gVF+0viv5uCftFxn2bRuzq9Bf+rFrftUBM2JJDYFKuInMICEz89UvYjkm/h3iqHB6RHKbyEl3sBTheToobIAB9WYXcX2IaKJ6ri0mlW8ltzMW6+HZFN3Rz5t7xwkxvC9HZ94quDT0iI8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787664938; c=relaxed/simple; bh=wJRA2NQzvpo1UzXOUXeJv36StzFer0WN+FQIe3tBYa0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fOxK9y8JrM31T1BOySeXMsJxkRSxZAm1ZZfnp+Fv3Huu32QbG6uzWz77Qi/GehlTWscOQYCERHtVhrHEAnbbWm3s0SkB26ChBCSeAcBFuoUxdgcNoLVvOrZIrQIY02vh5u4p6h6qBMtEzjcMnCfs+8NXL/3BNFGRaLO3r+SxuHU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DPa8yUfN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DPa8yUfN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4574E1F000E9; Tue, 25 Aug 2026 13:35:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787664933; bh=5l3Irf/R/v5YjadcdcZbQl1MUIPuxYDgZ3t2X/VJ5bg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DPa8yUfNTCPx1FFu2DTITz1ocbvaDNMGhl71YFPmtOTbjL2zQ3iInuh/FkSxSb1zl Y+w8wS60hWjJbQ+IRVSI2B/zOTiWZnJqKPwcgSQTSWjKGG2nOqkYnkHC+Ukx6sE8IP B0vDs4UNVlcaeuRM7FfSka+Ydn1Ew2fTMyRVghBo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christoph Hellwig , Ibrahim Hashimov , Keith Busch Subject: [PATCH 7.1 055/101] nvmet-tcp: bound SGL data length before allocating command buffers Date: Tue, 25 Aug 2026 15:25:33 +0200 Message-ID: <20260825132544.157727110@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.986300899@linuxfoundation.org> References: <20260825132541.986300899@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ibrahim Hashimov commit 4a3f00262a044e8e15064b1a6860968bf0500bf4 upstream. nvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length and, for the in-capsule offset descriptor (type 0x01), checks it against port->inline_data_size before use. Any other SGL descriptor type -- including the non-inline transport SGL data-block descriptor (type (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A, the type a real host uses for out-of-capsule writes) skips that check entirely and falls straight through to: cmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt); with len taken directly from the wire, unbounded up to 4 GiB. nvmet_req_init() only parses the command and never inspects sgl->length, and nvmet_check_transfer_len() -- the only other place transfer_len is validated -- runs later, from req->execute(), after the allocation has already happened. For a write command the target responds with an R2T and parks the command waiting for the host to send the data; if the host (or an unauthenticated peer that simply never follows up) never does, the sgl_alloc() buffer stays resident for the life of the command. NVMe/TCP has no mandatory authentication in the default configuration, so any peer able to reach the target portal and complete a Fabrics connect can drive this with a single crafted command, repeatable across queues and connections for amplification. This is unbounded kernel memory allocation triggered by a remote, effectively unauthenticated peer. Validate len against the same NVMET_TCP_MAXH2CDATA ceiling this file already uses to bound per-PDU H2C data, for every SGL descriptor type, before doing any allocation. This closes the gap for the non-inline descriptor while leaving the existing, tighter inline_data_size check in place for the in-capsule case. Runtime-verified on a v6.19 KASAN stand: with this bound in place, a crafted write command carrying an oversized non-inline SGL length is rejected before sgl_alloc() runs, where the same request previously drove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that stayed resident pending an R2T the host never satisfies. Fixes: 872d26a391da ("nvmet-tcp: add NVMe over TCP target driver") Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Ibrahim Hashimov Assisted-by: AuditCode-AI:2026.07 Signed-off-by: Keith Busch Signed-off-by: Greg Kroah-Hartman --- drivers/nvme/target/tcp.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/drivers/nvme/target/tcp.c +++ b/drivers/nvme/target/tcp.c @@ -422,6 +422,19 @@ static int nvmet_tcp_map_data(struct nvm if (!len) return 0; + /* + * inline_data_size only bounds the in-capsule (type 0x01) SGL + * descriptor below. A non-inline transport SGL data-block + * descriptor skips that check entirely and would otherwise reach + * sgl_alloc() with an attacker-controlled len of up to 4 GiB, + * pinning that much kernel memory for a command that may never + * complete. Bound every descriptor type here, before allocating + * anything, using the same ceiling this file already applies to + * per-PDU H2C data. + */ + if (len > NVMET_TCP_MAXH2CDATA) + return NVME_SC_SGL_INVALID_DATA | NVME_STATUS_DNR; + if (sgl->type == ((NVME_SGL_FMT_DATA_DESC << 4) | NVME_SGL_FMT_OFFSET)) { if (!nvme_is_write(cmd->req.cmd))