sctp: fix NULL deref on untransmitted RECONF completion

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89477
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:29 UTC
Updated2026-09-11 20:19:29 UTC
DescriptionIn 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: <IRQ> 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) </IRQ> 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 81054476453640159149cb6704e834893e16736b 77ea60f2d24002c308f224db44a4542c466489af git Not specified
CNA Linux Linux affected 81054476453640159149cb6704e834893e16736b 25419f516ea84b1e7d3d55aae5215ac86ece0c66 git Not specified
CNA Linux Linux affected 81054476453640159149cb6704e834893e16736b 0ee697defc0594f1da810ed75d9d643fb46f5318 git Not specified
CNA Linux Linux affected 81054476453640159149cb6704e834893e16736b 2db9bfa3e27bdea15e05ea70b56bad3d21e570ec git Not specified
CNA Linux Linux affected 4.11 Not specified
CNA Linux Linux unaffected 4.11 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/25419f516ea84b1e7d3d55aae5215ac86ece0c66 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0ee697defc0594f1da810ed75d9d643fb46f5318 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2db9bfa3e27bdea15e05ea70b56bad3d21e570ec 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/77ea60f2d24002c308f224db44a4542c466489af 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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