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 CFB1C481255; Tue, 25 Aug 2026 13:40:38 +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=1787665241; cv=none; b=On85xjg5oe9KDjLHKiABbkXmIhpjpdCksGg4wta/M7Fm3x963LbnGK2ou2OZjHfPWIQAT97QgztVGSqfEW52MC5KUXA6bBLAq+bhhWVis9OXpuLo45pYLe/YEsQ5wJgqE6EjRLEXVzt0aFedoGWVmQ+UXHYg9JzdV71CdLepPOY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665241; c=relaxed/simple; bh=IUBWcn1Hp1+UBdNg1yDeuisTJBZ7dvhDL0tkbeBK59M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=noHVinqKg/hhzE/fITmI1xpdu2XcyFUH8NONVk//PqdSb31v/uZJEQpQe5MVcuJh1tPAenssgXpdPlHCLIKXdPjkZ1HlyM3/iFZHVBaT4tejSbr437t0tEprAg8jx0AQ4AfTQ5IiAneT/uI21LmfOWMpZwe/v/SdpGbT/29n7wY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=P57rRgKY; 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="P57rRgKY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 253951F000E9; Tue, 25 Aug 2026 13:40:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787665238; bh=ySX8fZ7hvRwRUxFx1ex6jwBTWc9tK2KNGk83cl7rKUs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=P57rRgKYDzNTOf3WxiFyRHIagn9cGug2DRIUKNKn62r6vJtjGNIrRkLkPa60HURf6 bDFEujWbPRvs0fo5TZrAJ8MxrF5G/+2N3aLX+L1Ms/6BcfO57f0RY21bX4skqE5xZK v3w5Do7VcyJTTfZZsPaHbGsKH31wtEGlotuIkSEI= 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 6.18 53/94] nvmet-tcp: bound SGL data length before allocating command buffers Date: Tue, 25 Aug 2026 15:25:49 +0200 Message-ID: <20260825132543.981156042@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.887883084@linuxfoundation.org> References: <20260825132541.887883084@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 6.18-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 @@ -433,6 +433,19 @@ 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))