Bug 2516842 (CVE-2026-74268)

Summary:	CVE-2026-74268 kernel: tcp: clear sock_ops cb flags before force-closing a child socket
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel. A race condition exists in the TCP (Transmission Control Protocol) component when handling child sockets. If a child socket's setup fails, it can inherit BPF (Berkeley Packet Filter) socket operation flags, leading to a situation where the system attempts to call a BPF function without the necessary socket lock. This can result in a kernel panic, causing a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-15 06:36:19 UTC

In the Linux kernel, the following vulnerability has been resolved:

tcp: clear sock_ops cb flags before force-closing a child socket

A child socket inherits the listener's bpf_sock_ops_cb_flags via
sk_clone_lock(). If its setup fails in tcp_v4_syn_recv_sock() /
tcp_v6_syn_recv_sock(), the child is freed through put_and_exit, where
inet_csk_prepare_forced_close() drops the socket lock and tcp_done() runs
without it.

If BPF_SOCK_OPS_STATE_CB_FLAG was inherited, tcp_done() -> tcp_set_state()
calls tcp_call_bpf(), which expects the lock and trips sock_owned_by_me():

  WARNING: include/net/sock.h:1799 at tcp_set_state+0x433/0x550
  RIP: 0010:tcp_set_state+0x433/0x550 include/net/sock.h:1799
  Call Trace:
   <IRQ>
   tcp_done+0xba/0x250 net/ipv4/tcp.c:5095
   tcp_v4_syn_recv_sock+0x850/0xa50 net/ipv4/tcp_ipv4.c:1787
   tcp_check_req+0xf30/0x1360 net/ipv4/tcp_minisocks.c:926
   tcp_v4_rcv+0x1047/0x1b50 net/ipv4/tcp_ipv4.c:2164
   </IRQ>

The child is freed before it is ever established, so it should run no
sock_ops callback. Clear its cb flags in inet_csk_prepare_for_destroy_sock(),
the common point for the IPv4, IPv6 and chtls forced-close paths and for the
MPTCP ->syn_recv_sock() failure path (dispose_child), which reaches tcp_done()
on a child that was never established too.