In the Linux kernel, the following vulnerability has been resolved:
ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()
pmc->sflist is read locklessly under rcu_read_lock() by
inet6_mc_check() during packet reception in the UDP and RAW
multicast receive paths.
ip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place
when adding or removing a source filter. Additionally, when expanding
the filter buffer, newpsl was published via rcu_assign_pointer()
before writing the new source into the array.
Because 16-byte struct in6_addr writes are not atomic and array
shifting is not synchronized with RCU readers, concurrent readers in
inet6_mc_check() could read torn IPv6 addresses or observe
duplicated/missed source entries.
Fix this by switching ip6_mc_source() to copy-on-write RCU updates:
allocate and fully populate newpsl before publishing it via
rcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),
matching ip6_mc_msfilter().
Also remove the now unused IP6_SFBLOCK macro.
ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()
pmc->sflist is read locklessly under rcu_read_lock() by
inet6_mc_check() during packet reception in the UDP and RAW
multicast receive paths.
ip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place
when adding or removing a source filter. Additionally, when expanding
the filter buffer, newpsl was published via rcu_assign_pointer()
before writing the new source into the array.
Because 16-byte struct in6_addr writes are not atomic and array
shifting is not synchronized with RCU readers, concurrent readers in
inet6_mc_check() could read torn IPv6 addresses or observe
duplicated/missed source entries.
Fix this by switching ip6_mc_source() to copy-on-write RCU updates:
allocate and fully populate newpsl before publishing it via
rcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),
matching ip6_mc_msfilter().
Also remove the now unused IP6_SFBLOCK macro.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 25 Sep 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source() pmc->sflist is read locklessly under rcu_read_lock() by inet6_mc_check() during packet reception in the UDP and RAW multicast receive paths. ip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place when adding or removing a source filter. Additionally, when expanding the filter buffer, newpsl was published via rcu_assign_pointer() before writing the new source into the array. Because 16-byte struct in6_addr writes are not atomic and array shifting is not synchronized with RCU readers, concurrent readers in inet6_mc_check() could read torn IPv6 addresses or observe duplicated/missed source entries. Fix this by switching ip6_mc_source() to copy-on-write RCU updates: allocate and fully populate newpsl before publishing it via rcu_assign_pointer(), and reclaim the old filter via kfree_rcu(), matching ip6_mc_msfilter(). Also remove the now unused IP6_SFBLOCK macro. | |
| Title | ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-25T10:35:52.731Z
Reserved: 2026-09-25T10:25:14.315Z
Link: CVE-2026-98101
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.