bridge: guard local VLAN-0 FDB helpers against NULL vlan group

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Summary

CVECVE-2026-43100
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-06 10:16:23 UTC
Updated2026-05-06 13:07:51 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bridge: guard local VLAN-0 FDB helpers against NULL vlan group When CONFIG_BRIDGE_VLAN_FILTERING is not set, br_vlan_group() and nbp_vlan_group() return NULL (br_private.h stub definitions). The BR_BOOLOPT_FDB_LOCAL_VLAN_0 toggle code is compiled unconditionally and reaches br_fdb_delete_locals_per_vlan_port() and br_fdb_insert_locals_per_vlan_port(), where the NULL vlan group pointer is dereferenced via list_for_each_entry(v, &vg->vlan_list, vlist). The observed crash is in the delete path, triggered when creating a bridge with IFLA_BR_MULTI_BOOLOPT containing BR_BOOLOPT_FDB_LOCAL_VLAN_0 via RTM_NEWLINK. The insert helper has the same bug pattern. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000056: 0000 [#1] KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000002b0-0x00000000000002b7] RIP: 0010:br_fdb_delete_locals_per_vlan+0x2b9/0x310 Call Trace: br_fdb_toggle_local_vlan_0+0x452/0x4c0 br_toggle_fdb_local_vlan_0+0x31/0x80 net/bridge/br.c:276 br_boolopt_toggle net/bridge/br.c:313 br_boolopt_multi_toggle net/bridge/br.c:364 br_changelink net/bridge/br_netlink.c:1542 br_dev_newlink net/bridge/br_netlink.c:1575 Add NULL checks for the vlan group pointer in both helpers, returning early when there are no VLANs to iterate. This matches the existing pattern used by other bridge FDB functions such as br_fdb_add() and br_fdb_delete().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 21446c06b441b9c993870efae71aef4e9aa72ec7 fb612d436ff0317659e45a91c25fd7d9516f5b1b git Not specified
CNA Linux Linux affected 21446c06b441b9c993870efae71aef4e9aa72ec7 ddf0ec2d600e7dad62b89692749534d7900a732a git Not specified
CNA Linux Linux affected 21446c06b441b9c993870efae71aef4e9aa72ec7 1979645e1842cb7017525a61a0e0e0beb924d02a git Not specified
CNA Linux Linux affected 6.18 Not specified
CNA Linux Linux unaffected 6.18 semver Not specified
CNA Linux Linux unaffected 6.18.24 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.14 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/1979645e1842cb7017525a61a0e0e0beb924d02a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fb612d436ff0317659e45a91c25fd7d9516f5b1b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ddf0ec2d600e7dad62b89692749534d7900a732a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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