Medium [CVE-2024-36905] tcp: defer shutdown(SEND_SHUTDOWN) for TCP_SYN_RECV sockets
This medium-severity Red Hat Linux advisory covers CVE-2024-36905 affecting Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.4 Extended Update Support, Red Hat Enterprise Linux 6.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
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Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: defer shutdown(SEND_SHUTDOWN) for TCP_SYN_RECV sockets TCP_SYN_RECV state is really special, it is only used by cross-syn connections, mostly used by fuzzers.
In the following crash [1], syzbot managed to trigger a divide by zero in tcp_rcv_space_adjust() A socket makes the following state transitions, without ever calling tcp_init_transfer(), meaning tcp_init_buffer_space() is also not called.
TCP_CLOSE connect() TCP_SYN_SENT TCP_SYN_RECV shutdown() -> tcp_shutdown(sk, SEND_SHUTDOWN) TCP_FIN_WAIT1 To fix this issue, change tcp_shutdown() to not perform a TCP_SYN_RECV -> TCP_FIN_WAIT1 transition, which makes no sense anyway.
When tcp_rcv_state_process() later changes socket state from TCP_SYN_RECV to TCP_ESTABLISH, then look at sk->sk_shutdown to finally enter TCP_FIN_WAIT1 state, and send a FIN packet from a sane socket state.
Affected products named by the advisory: Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.4 Extended Update Support; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; and 1 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 7 hours ago·verify at source
- kernel-rt-0:4.18.0-553.16.1.rt7.357.el8_10
- kernel-0:4.18.0-553.16.1.el8_10
- kernel-0:5.14.0-503.11.1.el9_5
- kernel-0:5.14.0-427.57.1.el9_4
- RHSA-2024:5102
- RHSA-2024:5101
- RHSA-2024:9315
- RHSA-2025:2270
Official advisory · high-confidence parse· fetched 7 hours ago·verify at source
Mitigation
Upgrade to a fixed release: kernel-rt-0:4.18.0-553.16.1.rt7.357.el8_10, kernel-0:4.18.0-553.16.1.el8_10, kernel-0:5.14.0-503.11.1.el9_5, kernel-0:5.14.0-427.57.1.el9_4, RHSA-2024:5102, RHSA-2024:5101. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 7 hours ago·verify at source
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