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 48AA840EBA9 for ; Fri, 11 Sep 2026 19:52:23 +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=1789156351; cv=none; b=S+Uq2cJsB4P+VloFp4RmadM4thklOJx6ejWRsCLK5ech9c2muW3ZOKNVmBQ8ceH9IBeP0mZo+8Qoa2Ml9N8jfOMUixi//8u0xVZiRjlSRdx0rv1XvSPRurZ3mZLRalira/5IGiEjG3taN2sDJ99aVMhx5Zjpg79VtlMBHV8eX04= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156351; c=relaxed/simple; bh=WQLKcSzrsY/5VwpCDXPlEEA29jmiZLtYNu8bblHiO3Q=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Qiiq7+1PCgk/8Zfajx2e2JR3m46eoJqtcwjUFtO8tsWisHltC0oazfgACUnHfRFRMAET0SaGIMxf1MKyo0huI0NwkG3ehiW84WFzNaV7cswo8dqruPW4yBahuziUb/DwnbfwfmzdjvA40g98eDYsDtw3B3139yXWn0rGXlM2NO8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=y+R+tkpy; 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="y+R+tkpy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63CB51F00898; Fri, 11 Sep 2026 19:52:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156340; bh=7XpdRvUTYTRvm0kSLVvaBNZrVS5PGjJ+Pw+9sY++nD8=; h=From:To:Cc:Subject:Date:Reply-To; b=y+R+tkpyKYLMmdh9hkhZ9faV1YYwco8Mw3qYJ9Js9I+UD84ksXVYEENO8rViXhghm mQvoDu3pNtZ0j/FS6OALqI6WOU0gAm88OrVMhXXJk3PIJm4ei6G/+ItxnnKhM85KFM 5U2ErfqDXYJhLkrRzoEcUGGF660zfcUiZt6SVDGI= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89477: sctp: fix NULL deref on untransmitted RECONF completion Date: Fri, 11 Sep 2026 21:42:46 +0200 Message-ID: <2026091104-CVE-2026-89477-ac6c@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4367; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=kCdl0iGwoyV/6ChVHP1oWgoRbf9/iW72Z9SgBT+eq5g=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIgPs6zIcbCKOt/6RPvOn1UQie+or58m6Im6zSrOSn whUT/XtiGVhEGRikBVTZPmyjefo/opDil6Gtqdh5rAygQxh4OIUgImIMDIsaAy+o7t0ZYpFkUW4 8SeRTyGZkZ89GBbslP4fpW9+PufFTF0RzqSHk2anXjwIAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: sctp: fix NULL deref on untransmitted RECONF completion sctp_process_strreset_outreq(), sctp_process_strreset_addstrm_out() and sctp_process_strreset_resp() complete a pending stream reconfiguration request by stopping the reconf timer on the transport it was sent on: t = asoc->strreset_chunk->transport; if (timer_delete(&t->reconf_timer)) sctp_transport_put(t); chunk->transport is assigned by __sctp_packet_append_chunk() when the chunk is appended to an outbound packet, and sctp_outq_flush_ctrl() arms the reconf timer at that same point. A request already published in asoc->strreset_chunk but not yet transmitted has neither, so completing it dereferences NULL. Two ways to get there. sctp_send_asconf_del_ip() sets asoc->src_out_of_asoc_ok without sending anything when the address being removed is the association's last one, and sctp_outq_flush_ctrl() then leaves every non-ASCONF control chunk queued; as only sctp_process_asconf_ack() clears that flag, it persists. An unprivileged process that removes such an address and then asks for a stream reset panics the kernel from softirq. A peer needs neither ASCONF nor local help: sctp_cmd_interpreter() uncorks the outqueue only once the whole packet has been processed, so a reply built while walking a RECONF chunk stays untransmitted for the rest of that walk, and one RECONF chunk carrying [Incoming SSN Reset Request, Outgoing SSN Reset Request, Response] -- or two RECONF chunks in one packet -- reaches the same dereference. KASAN: null-ptr-deref in range [0x00000000000001e8-0x00000000000001ef] RIP: 0010:timer_delete+0x67/0x110 Call Trace: sctp_process_strreset_addstrm_out (net/sctp/stream.c:832) sctp_sf_do_reconf (net/sctp/sm_statefuns.c:4212) sctp_do_sm (net/sctp/sm_sideeffect.c:1172) sctp_assoc_bh_rcv (net/sctp/associola.c:1044) sctp_rcv (net/sctp/input.c:243) ip_local_deliver (net/ipv4/ip_input.c:262) process_backlog (net/core/dev.c:6680) A response can only acknowledge a request that was actually sent, so do not match asoc->strreset_chunk while chunk->transport is NULL. Guarding the lookup covers all three completion sites. The Linux kernel CVE team has assigned CVE-2026-89477 to this issue. Affected and fixed versions =========================== Issue introduced in 4.11 with commit 81054476453640159149cb6704e834893e16736b and fixed in 6.12.109 with commit 77ea60f2d24002c308f224db44a4542c466489af Issue introduced in 4.11 with commit 81054476453640159149cb6704e834893e16736b and fixed in 6.18.50 with commit 25419f516ea84b1e7d3d55aae5215ac86ece0c66 Issue introduced in 4.11 with commit 81054476453640159149cb6704e834893e16736b and fixed in 7.2.4 with commit 0ee697defc0594f1da810ed75d9d643fb46f5318 Issue introduced in 4.11 with commit 81054476453640159149cb6704e834893e16736b and fixed in 7.3-rc1 with commit 2db9bfa3e27bdea15e05ea70b56bad3d21e570ec Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-89477 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: net/sctp/stream.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/77ea60f2d24002c308f224db44a4542c466489af https://git.kernel.org/stable/c/25419f516ea84b1e7d3d55aae5215ac86ece0c66 https://git.kernel.org/stable/c/0ee697defc0594f1da810ed75d9d643fb46f5318 https://git.kernel.org/stable/c/2db9bfa3e27bdea15e05ea70b56bad3d21e570ec