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 5DFBF33CE8A; Thu, 28 May 2026 20:37:05 +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=1780000626; cv=none; b=qx+4wz5ZJlxT/DXhcXO4JSs19WQJsM5/WL2vFst0xtJa7pa3T54Slf7cGjKfhWpqZAOAQQwc6JshgXZohwlwcPuhtWLTkj4PyUF+2UgFnL9fIaXn9h79AlzpRQ/1x/My3kZN1/NEvSAZmgmxtAu+98aMyLHMLetQs1MZV3BzBeo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780000626; c=relaxed/simple; bh=zdHRx0Y65XFJhXdTGaatb28nfDeOKBUbk55D8YIbvBs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eUIgQs2bDrv6h+P/XIaVpcNjBAlnInZTyR+nhSbbMhG4AxHJpTwl20ruAFs7Dbspqr0qj7L78o9GCOH61Fq9ASVzB/R03L7bm0s1faI5Yu84S6AMoA1uVocxOZdMrPqN1neHwtvzwaPiPjZ3jEy4xI1//1HVU6uS6MltlgoKSnE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MyYPP8l4; 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="MyYPP8l4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC58C1F000E9; Thu, 28 May 2026 20:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780000625; bh=bQ2AbuXOPJVXXFX64Yv4X9mYmDRTBggGjKmXJYYHSRY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MyYPP8l4WHMMWhfVhH7SepDXXRx9hXcRnU/WGFBNEsGgJGsFZYIWqkNVBC6IrEqn8 G9BC8Mx22/aUhfv9xqmkB5hsEfigLGi8dl9rMTJt9yDC8VCUwy1ZDhU5s004fiw3fH bj3xCF6oOiTnasL6AYMQpsA2VtC5dZ2jelItCzg0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Michael Bommarito , Bernard Metzler , Jason Gunthorpe Subject: [PATCH 6.12 111/272] RDMA/siw: Reject MPA FPDU length underflow before signed receive math Date: Thu, 28 May 2026 21:48:05 +0200 Message-ID: <20260528194632.487706262@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194629.379955525@linuxfoundation.org> References: <20260528194629.379955525@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Bommarito commit 0ce1bc9e46ecabe84772bb561e373c0d9876d6f2 upstream. A malicious connected siw peer can send an iWARP FPDU whose MPA length field (c_hdr->mpa_len, 16 bit big-endian, peer-controlled) is smaller than the fixed DDP/RDMAP header for the announced opcode. Soft-iWARP parses the full header in siw_get_hdr() based on iwarp_pktinfo[opcode] .hdr_len, but never compares mpa_len against that header length. siw_tcp_rx_data() then derives srx->fpdu_part_rem = be16_to_cpu(mpa_len) - fpdu_part_rcvd + MPA_HDR_SIZE; where fpdu_part_rcvd equals iwarp_pktinfo[opcode].hdr_len at this point. For a tagged WRITE (hdr_len 16, MPA_HDR_SIZE 2) the smallest on-wire mpa_len of 0 yields fpdu_part_rem = -14, and any mpa_len below hdr_len - MPA_HDR_SIZE underflows to a negative int. The signed value then flows into siw_proc_write()/siw_proc_rresp() as bytes = min(srx->fpdu_part_rem, srx->skb_new); is handed to siw_check_mem() as an int len (whose interval check addr + len > mem->va + mem->len is satisfied for a valid base when len is negative), and reaches siw_rx_data() -> siw_rx_kva() / siw_rx_umem() -> skb_copy_bits() as a signed copy length. The header copy branch in skb_copy_bits() promotes that to size_t, producing a multi-gigabyte read. KASAN under a KUnit harness that drives the real kernel TCP receive path -- a loopback AF_INET socketpair, the malformed FPDU written via kernel_sendmsg, sk_data_ready firing in softirq, tcp_read_sock dispatching to siw_tcp_rx_data -- reports: BUG: KASAN: use-after-free in skb_copy_bits+0x284/0x480 Read of size 4294967295 at addr ffff888... Call Trace: skb_copy_bits siw_rx_kva siw_rx_data siw_check_mem siw_proc_write siw_tcp_rx_data __tcp_read_sock siw_qp_llp_data_ready tcp_data_ready tcp_data_queue Add the missing invariant at the earliest point where the peer header is fully assembled. iwarp_pktinfo[*].hdr_len - MPA_HDR_SIZE is exactly the value the siw transmitter uses as the minimum mpa_len for each opcode (drivers/infiniband/sw/siw/siw_qp.c:33), so this matches the protocol contract. Out-of-range FPDUs terminate the connection with TERM_ERROR_LAYER_LLP / LLP_ETYPE_MPA / LLP_ECODE_FPDU_START -- which is RFC 5044 Section 8 error code 3 ("Marker and ULPDU Length fields do not agree on the start of an FPDU"), the correct framing-error class for this inconsistency. Fixes: 8b6a361b8c48 ("rdma/siw: receive path") Link: https://patch.msgid.link/r/20260513175325.2042630-2-michael.bommarito@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Michael Bommarito Assisted-by: Claude:claude-opus-4-7 Acked-by: Bernard Metzler Signed-off-by: Jason Gunthorpe Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/sw/siw/siw_qp_rx.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) --- a/drivers/infiniband/sw/siw/siw_qp_rx.c +++ b/drivers/infiniband/sw/siw/siw_qp_rx.c @@ -1082,6 +1082,21 @@ static int siw_get_hdr(struct siw_rx_str } /* + * Peer-controlled mpa_len must not underflow srx->fpdu_part_rem + * in siw_tcp_rx_data(); a negative value flows as a signed copy + * length into siw_check_mem() and skb_copy_bits(). + */ + if (unlikely(be16_to_cpu(c_hdr->mpa_len) + MPA_HDR_SIZE < + iwarp_pktinfo[opcode].hdr_len)) { + pr_warn_ratelimited("siw: short mpa_len %u for opcode %u (hdr_len %u)\n", + be16_to_cpu(c_hdr->mpa_len), opcode, + iwarp_pktinfo[opcode].hdr_len); + siw_init_terminate(rx_qp(srx), TERM_ERROR_LAYER_LLP, + LLP_ETYPE_MPA, LLP_ECODE_FPDU_START, 0); + return -EINVAL; + } + + /* * DDP/RDMAP header receive completed. Check if the current * DDP segment starts a new RDMAP message or continues a previously * started RDMAP message.