Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock nfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with list_for_each_entry_safe(ni, tmp, ...). For each expired entry it sets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the source vfsmount, then reacquires the lock to list_del + kfree the entry and continue iterating via the macro's saved tmp pointer. The nsui_busy flag protects the current ni from concurrent nfsd4_ssc_setup_dul() finders during the lock-drop window, but it does not pin tmp. Another nfsd RPC thread that fails its source- server mount and reaches nfsd4_ssc_cancel_dul() will, during that same window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount item, and release the lock. If that item is the saved tmp of the expire walk, the next iteration dereferences a freed nfsd4_ssc_umount_item. Restart the walk from the head after the mntput() unlock window so no saved next pointer survives the lock-drop. The list is bounded by the number of active inter-server source mounts (typically small) and the expire delayed-work runs periodically rather than per-IO, so the restart is cheap.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
a4bc287943f5695209ff36bdc89f17b48d68fae7 to < 2b59029b8f24a99b5d844af2da3950d39d36eeeaaffectedf4e44b393389c77958f7c58bf4415032b4cda15b to < d9e151fea5ed706c1284adacabd869b0be745db2affectedf4e44b393389c77958f7c58bf4415032b4cda15b to < 659ee3da073164e1e6e40dfcbc26eeed85845f93affectedf4e44b393389c77958f7c58bf4415032b4cda15b to < 60680ae7243b22de3d09be990d8e23bcfc4af837affectedf4e44b393389c77958f7c58bf4415032b4cda15b to < 77de363d9a1c8cd35f20482782c612cda085791aaffectedf4e44b393389c77958f7c58bf4415032b4cda15b to < 4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8affectedf4e44b393389c77958f7c58bf4415032b4cda15b to < 7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9affectedf4e44b393389c77958f7c58bf4415032b4cda15b to < 036c1b182f4da65363e79ec0ac276edc6b7296e5affected5.10.220 to < 5.10.270affected
Linux Linux
Default version status: affected
5.14affected0 to < 5.14unaffected5.10.270 to ≤ 5.10.*unaffected5.15.221 to ≤ 5.15.*unaffected6.1.188 to ≤ 6.1.*unaffected6.6.157 to ≤ 6.6.*unaffected6.12.109 to ≤ 6.12.*unaffected6.18.50 to ≤ 6.18.*unaffected7.2.4 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/2b59029b8f24a99b5d844af2da3950d39d36eeea ↗
- https://git.kernel.org/stable/c/d9e151fea5ed706c1284adacabd869b0be745db2 ↗
- https://git.kernel.org/stable/c/659ee3da073164e1e6e40dfcbc26eeed85845f93 ↗
- https://git.kernel.org/stable/c/60680ae7243b22de3d09be990d8e23bcfc4af837 ↗
- https://git.kernel.org/stable/c/77de363d9a1c8cd35f20482782c612cda085791a ↗
- https://git.kernel.org/stable/c/4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8 ↗
- https://git.kernel.org/stable/c/7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9 ↗
- https://git.kernel.org/stable/c/036c1b182f4da65363e79ec0ac276edc6b7296e5 ↗