Bug 2393166 (CVE-2025-38718)

Summary:	CVE-2025-38718 kernel: sctp: linearize cloned gso packets in sctp_rcv
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	Keywords:	Security
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw use of uninitialized memory (uncontrolled and invisible by attacker) in the Linux kernel SCTP transport protocol was found in the way user triggers malicious SCTP packets. A remote user could use this flaw to crash the system. The bug actual only for systems where SCTP protocol being enabled and used.	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 2025-09-04 16:02:15 UTC

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

sctp: linearize cloned gso packets in sctp_rcv

A cloned head skb still shares these frag skbs in fraglist with the
original head skb. It's not safe to access these frag skbs.

syzbot reported two use-of-uninitialized-memory bugs caused by this:

  BUG: KMSAN: uninit-value in sctp_inq_pop+0x15b7/0x1920 net/sctp/inqueue.c:211
   sctp_inq_pop+0x15b7/0x1920 net/sctp/inqueue.c:211
   sctp_assoc_bh_rcv+0x1a7/0xc50 net/sctp/associola.c:998
   sctp_inq_push+0x2ef/0x380 net/sctp/inqueue.c:88
   sctp_backlog_rcv+0x397/0xdb0 net/sctp/input.c:331
   sk_backlog_rcv+0x13b/0x420 include/net/sock.h:1122
   __release_sock+0x1da/0x330 net/core/sock.c:3106
   release_sock+0x6b/0x250 net/core/sock.c:3660
   sctp_wait_for_connect+0x487/0x820 net/sctp/socket.c:9360
   sctp_sendmsg_to_asoc+0x1ec1/0x1f00 net/sctp/socket.c:1885
   sctp_sendmsg+0x32b9/0x4a80 net/sctp/socket.c:2031
   inet_sendmsg+0x25a/0x280 net/ipv4/af_inet.c:851
   sock_sendmsg_nosec net/socket.c:718 [inline]

and

  BUG: KMSAN: uninit-value in sctp_assoc_bh_rcv+0x34e/0xbc0 net/sctp/associola.c:987
   sctp_assoc_bh_rcv+0x34e/0xbc0 net/sctp/associola.c:987
   sctp_inq_push+0x2a3/0x350 net/sctp/inqueue.c:88
   sctp_backlog_rcv+0x3c7/0xda0 net/sctp/input.c:331
   sk_backlog_rcv+0x142/0x420 include/net/sock.h:1148
   __release_sock+0x1d3/0x330 net/core/sock.c:3213
   release_sock+0x6b/0x270 net/core/sock.c:3767
   sctp_wait_for_connect+0x458/0x820 net/sctp/socket.c:9367
   sctp_sendmsg_to_asoc+0x223a/0x2260 net/sctp/socket.c:1886
   sctp_sendmsg+0x3910/0x49f0 net/sctp/socket.c:2032
   inet_sendmsg+0x269/0x2a0 net/ipv4/af_inet.c:851
   sock_sendmsg_nosec net/socket.c:712 [inline]

This patch fixes it by linearizing cloned gso packets in sctp_rcv().

Comment 1 Jon Moroney 2025-09-04 20:19:10 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025090459-CVE-2025-38718-5bb6@gregkh/T

Comment 4 errata-xmlrpc 2025-09-29 05:05:41 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2025:16880 https://access.redhat.com/errata/RHSA-2025:16880

Comment 5 errata-xmlrpc 2025-09-29 10:19:08 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2025:16920 https://access.redhat.com/errata/RHSA-2025:16920

Comment 6 errata-xmlrpc 2025-09-29 12:10:07 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2025:16919 https://access.redhat.com/errata/RHSA-2025:16919

Comment 8 errata-xmlrpc 2025-10-07 06:10:43 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2025:17396 https://access.redhat.com/errata/RHSA-2025:17396