From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210097; b=fhHIMlcPo3zDfdMJHtHVhPrhn9GHIb5eTN1WSAEISA3ku92Y8It0q8YeQ2UhI9pancre oxSJkam2tbY9HsBNFTE3lSxFyq8WvN9HpPJQDwqrK09/DlQ+sEv6jNXvZ6s4WIl3Shi9k Li/UvEfTPaTRRvWLCNegGyCPHEPzG50vAUfbsLUbI3l4kqHuVyVvLNedXPiqXtBi4XlSJ S7aCe2dgZGuCDPeioBQZkSL63so2bBjt1TgzRElM7m1J/Qe1ULgsB8ph0GTPBDy3+jFzk TDx51YIeo/jyT5gAG/de9FxWx5vVxAfEsdGV8qY1vxBfoGS+wWgPA+kVM7GGpDmLsfQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210097; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=W13OnIou1GGiRUgrBOuO/+UxCmU3Hgbz3cV9rVArYqs=; b=IRgPdnBLZKjgFR1cg0MPmj86KRFgZ0hBvoDDcyIoTM3FlyX4JWGMcWT0GVwziCeBUC1T Et4BtXPxCGFQR4IMkyczUOleED2eyghZ8SusevXGWC0C851Ve3xCW9xGVwqQrsZGKl0OK LysOIpHr2jpntgxkofmwplMVTCyAtQ2itO7dzzbZzuMTpg50PTpkUuZABn186lQyu322A 9n9FzzFpuBSDxp+Y25b4c3oHGWRxePWgQqzwkACrMMJ2/G5PIigxV/VLt802neOEj5mfS EAikjRokijwhlRqGLE9Fuu8AnhITaaSDEVmRuYlgGxvHB/bLMS/4q5sobKmOp5ODKGw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=PLMJDsDg; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EDC6C606A32D; Wed, 28 Oct 2026 17:54:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=PLMJDsDg Received: by smtp.kernel.org (Postfix) with ESMTPSA id 130951F01829; Wed, 28 Oct 2026 17:54:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210096; bh=W13OnIou1GGiRUgrBOuO/+UxCmU3Hgbz3cV9rVArYqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PLMJDsDg81n+FqXABULXIuD1wJXkIG9Ro5YDawKt2ROi89LPDS1CI6zlqb/FYZlj+ E4JlDA3mwbSsPTKkyKJ+zFiHHY9stsNyn3fY/1Dqd0cKxNSOttg8KUTN6Ex8E3VBEB U7KsAne47zw6HVqDHOOEhFtqNJYTnbe+OGWaFrow= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Charles Vosburgh , Xin Long , Jakub Kicinski Subject: [PATCH 6.6 075/168] sctp: validate chunk length in the inqueue parser Date: Wed, 28 Oct 2026 18:00:11 +0100 Message-ID: <20261028165944.860843166@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165943.089486480@linuxfoundation.org> References: <20261028165943.089486480@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Charles Vosburgh commit 6cfc1b90cb86f4aabc69fb8e30128e07e2cdfa3a upstream. SCTP chunks always include a four-byte generic header, but sctp_inq_pop() currently accepts shorter declared lengths. A zero-length chunk leaves chunk_end at the current header. When ASCONF is covered by the association's SCTP-AUTH policy, sctp_assoc_bh_rcv() can continue before the state machine performs its normal chunk-length check. sctp_inq_pop() then returns the same malformed chunk repeatedly and the receive softirq can lock up. A remote SCTP peer can trigger this after establishing an association on a kernel built with CONFIG_IP_SCTP and configured with net.sctp.addip_enable=1 and net.sctp.auth_enable=1. The reproducer did not require application credentials, a shared SCTP AUTH key, or net.sctp.addip_noauth_enable=1. On commit f967455fb2a5 ("seg6: reset IP6CB after IPv6 decapsulation"), one zero-length ASCONF caused repeated watchdog soft-lockup reports in a two-vCPU KVM guest. All 3 pre-trigger health probes succeeded, while 36 of 37 post-trigger probes failed. With this change, all 37 post-trigger probes succeeded and no equivalent soft-lockup signature appeared. Reject chunks shorter than the generic SCTP header at the shared inqueue parser boundary. Mark the packet for discard before either caller can continue processing it, while preserving the four-byte generic minimum. Declared-length 1 through 4 controls and kernel-generated ASCONF traffic remained healthy. The patched sctp_hello selftest passed for IPv4 and IPv6. The complete private reproducer and validation evidence are available directly to maintainers on request. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Cc: stable@vger.kernel.org Signed-off-by: Charles Vosburgh Acked-by: Xin Long Link: https://patch.msgid.link/20260827-sctp-zero-chunk-inqueue-v2-1-2e7669c6a6cb@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/sctp/inqueue.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/net/sctp/inqueue.c +++ b/net/sctp/inqueue.c @@ -212,8 +212,10 @@ new_skb: chunk->chunk_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); skb_pull(chunk->skb, sizeof(*ch)); chunk->subh.v = NULL; /* Subheader is no longer valid. */ - - if (chunk->chunk_end + sizeof(*ch) <= skb_tail_pointer(chunk->skb)) { + if (unlikely(ntohs(ch->length) < sizeof(*ch))) { + chunk->pdiscard = 1; + } else if (chunk->chunk_end + sizeof(*ch) <= + skb_tail_pointer(chunk->skb)) { /* This is not a singleton */ chunk->singleton = 0; } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {