Bug 2454827 (CVE-2026-23460)

Summary:	CVE-2026-23460 kernel: net/rose: fix NULL pointer dereference in rose_transmit_link on reconnect
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	unspecified	Keywords:	Security
Target Milestone:	---
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Hardware:	All
OS:	Linux
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Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's net/rose component. A local user can trigger a NULL pointer dereference by calling `connect()` a second time while a connection attempt is already in progress. This improper handling of concurrent connection attempts can lead to a system crash, resulting in a Denial of Service (DoS).	Story Points:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-04-03 16:02:57 UTC

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

net/rose: fix NULL pointer dereference in rose_transmit_link on reconnect

syzkaller reported a bug [1], and the reproducer is available at [2].

ROSE sockets use four sk->sk_state values: TCP_CLOSE, TCP_LISTEN,
TCP_SYN_SENT, and TCP_ESTABLISHED. rose_connect() already rejects
calls for TCP_ESTABLISHED (-EISCONN) and TCP_CLOSE with SS_CONNECTING
(-ECONNREFUSED), but lacks a check for TCP_SYN_SENT.

When rose_connect() is called a second time while the first connection
attempt is still in progress (TCP_SYN_SENT), it overwrites
rose->neighbour via rose_get_neigh(). If that returns NULL, the socket
is left with rose->state == ROSE_STATE_1 but rose->neighbour == NULL.
When the socket is subsequently closed, rose_release() sees
ROSE_STATE_1 and calls rose_write_internal() ->
rose_transmit_link(skb, NULL), causing a NULL pointer dereference.

Per connect(2), a second connect() while a connection is already in
progress should return -EALREADY. Add this missing check for
TCP_SYN_SENT to complete the state validation in rose_connect().

[1] https://syzkaller.appspot.com/bug?extid=d00f90e0af54102fb271
[2] https://gist.github.com/mrpre/9e6779e0d13e2c66779b1653fef80516

Comment 1 Jon Moroney 2026-04-03 18:44:12 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026040319-CVE-2026-23460-f1d1@gregkh/T