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: <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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
81054476453640159149cb6704e834893e16736b to < 79ff751311e80fa0370007e46a79a6d601685e75affected81054476453640159149cb6704e834893e16736b to < 53141db979687eae7dc6d29414cefc77034f967eaffected81054476453640159149cb6704e834893e16736b to < 68891125af5a5dfbca728809a16637a869bbe0dfaffected81054476453640159149cb6704e834893e16736b to < b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4affected81054476453640159149cb6704e834893e16736b to < 77ea60f2d24002c308f224db44a4542c466489afaffected81054476453640159149cb6704e834893e16736b to < 25419f516ea84b1e7d3d55aae5215ac86ece0c66affected81054476453640159149cb6704e834893e16736b to < 0ee697defc0594f1da810ed75d9d643fb46f5318affected81054476453640159149cb6704e834893e16736b to < 2db9bfa3e27bdea15e05ea70b56bad3d21e570ecaffected
Linux Linux
Default version status: affected
4.11affected0 to < 4.11unaffected5.10.270 to ≤ 5.10.*unaffected5.15.221 to ≤ 5.15.*unaffected6.1.188 to ≤ 6.1.*unaffected6.6.157 to ≤ 6.6.*unaffected6.12.109 to ≤ 6.12.*unaffected6.18.50 to ≤ 6.18.*unaffected7.2.4 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/79ff751311e80fa0370007e46a79a6d601685e75 ↗
- https://git.kernel.org/stable/c/53141db979687eae7dc6d29414cefc77034f967e ↗
- https://git.kernel.org/stable/c/68891125af5a5dfbca728809a16637a869bbe0df ↗
- https://git.kernel.org/stable/c/b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4 ↗
- 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 ↗