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 3CBB336997A for ; Wed, 26 Aug 2026 14:54:05 +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=1787756050; cv=none; b=Qs1nR5Ei1QWyPrDqX7/2iLACNKGlUZvFbge4+SYVRxmMKl6Pz/DH+cwL9fsMHfi5HOFy/kF072DdMz9CrIIKHehPBNciGGoU+0AKIMcrIihuu9XwJKxNQrZ53dTgQgS+rU/05dc2NXOip6/iJOLW6kFxnUF9AqyZPGLVJ++hGnQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787756050; c=relaxed/simple; bh=sftiNpcGsFavskhIjJZQmi3SjMjkvbW10mQVnYYS2Q0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ds/2lVJBkls9csdOIMFSz2Urd7dj3yfmvtQms98xb6lOLvQSbAn8yMdykD700113FvTkPkcj2mc6TlgDAYIJOG03F1iW2ElEN8wlJJ+YPOuAfnzSI4cqnO3ImT+GnHzqoNurAadl6RemJrlW5C/QzFLsTzTc2cyhbAOed4j0ovQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EszX0Bxv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EszX0Bxv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 542191F00A3E; Wed, 26 Aug 2026 14:54:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787756044; bh=TdYvZNW/DXtOnb0kH1kcBjHNPdK6cvyx/1bmYacqkIs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EszX0Bxvobe2bBB+22IqFtpjOINrifgwBQjpF6mOvGS8t1e7mqcYzLRM9lnx2C5wR Bq7uxi8TzVJDDxzomcnSBV6S2pZEmjSSTTG1Rsq6dcn/fASC0ImtEF+J6BS++j0oI3 dF1Uof6gyP0EK90ZGf1KNnsez4QgJmSfRPc3wCm61qD+tbb5r0z1ry/7ovpKXlfEIJ V9hX3rcJ83UgGg38EkPy8zdL9Z8RH6c6/intiwXYJti+eAA1oEyzoRDT5qehHKaof6 nYla0u+eZZEKCIpGyzm63Szpkzy3dIcYAiuSqihPSJ8n/6bXbsd2uzE41mhsRC5yxV H+Ttb0CgjZbpQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Ibrahim Hashimov , Christoph Hellwig , Keith Busch , Sasha Levin Subject: [PATCH 6.1.y 2/2] nvmet-tcp: bound SGL data length before allocating command buffers Date: Wed, 26 Aug 2026 10:54:01 -0400 Message-ID: <20260826145401.874903-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260826145401.874903-1-sashal@kernel.org> References: <2026082515-grandkid-mustang-e962@gregkh> <20260826145401.874903-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ibrahim Hashimov [ Upstream commit 4a3f00262a044e8e15064b1a6860968bf0500bf4 ] 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: Sasha Levin --- drivers/nvme/target/tcp.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c index 074ebc26727cc..3a4494ceef128 100644 --- a/drivers/nvme/target/tcp.c +++ b/drivers/nvme/target/tcp.c @@ -390,6 +390,19 @@ static int nvmet_tcp_map_data(struct nvmet_tcp_cmd *cmd) 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)) -- 2.53.0