Bug 2348531 (CVE-2025-21758)

Summary:	CVE-2025-21758 kernel: ipv6: mcast: add RCU protection to mld_newpack()
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:	dfreiber, drow, jburrell, mijjapur, rhel-process-autobot, vkumar, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in the Linux kernel's IPv6 multicast implementation. The `mld_newpack()` function can be called without proper locking mechanisms, specifically without holding RTNL or RCU protection. This improper synchronization can lead to memory allocation issues, potentially allowing a local attacker to cause a system crash or a Denial of Service (DoS).	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
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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 2025-02-27 03:02:15 UTC

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

ipv6: mcast: add RCU protection to mld_newpack()

mld_newpack() can be called without RTNL or RCU being held.

Note that we no longer can use sock_alloc_send_skb() because
ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep.

Instead use alloc_skb() and charge the net->ipv6.igmp_sk
socket under RCU protection.

Comment 1 Michal Findra 2025-02-27 15:44:20 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022604-CVE-2025-21758-9f8c@gregkh/T