CVE-2021-47507
Assigner: Linux
Published: 2024-05-24T15:01:53.401Z
State: PUBLISHED
descriptions: value: In the Linux kernel, the following vulnerability has been resolved:

nfsd: Fix nsfd startup race (again)

Commit bd5ae9288d64 ("nfsd: register pernet ops last, unregister first")
has re-opened rpc_pipefs_event() race against nfsd_net_id registration
(register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76
("nfsd: fix nsfd startup race triggering BUG_ON").

Restore the order of register_pernet_subsys() vs register_cld_notifier().
Add WARN_ON() to prevent a future regression.

Crash info:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000012
CPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1
pc : rpc_pipefs_event+0x54/0x120 [nfsd]
lr : rpc_pipefs_event+0x48/0x120 [nfsd]
Call trace:
 rpc_pipefs_event+0x54/0x120 [nfsd]
 blocking_notifier_call_chain
 rpc_fill_super
 get_tree_keyed
 rpc_fs_get_tree
 vfs_get_tree
 do_mount
 ksys_mount
 __arm64_sys_mount
 el0_svc_handler
 el0_svc
affected: product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 8677e99150b0
lessThan: f5734b1714ca
status: affected
versionType: git
version: 7c7cb07d4aff
lessThan: c520943a00ad
status: affected
versionType: git
version: bd5ae9288d64
lessThan: 8bf902fee589
status: affected
versionType: git
version: bd5ae9288d64
lessThan: b10252c7ae9c
status: affected
versionType: git
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 5.12
status: affected
version: 0
lessThan: 5.12
status: unaffected
versionType: custom
version: 5.4.165
lessThanOrEqual: 5.4.*
status: unaffected
versionType: custom
version: 5.10.85
lessThanOrEqual: 5.10.*
status: unaffected
versionType: custom
version: 5.15.8
lessThanOrEqual: 5.15.*
status: unaffected
versionType: custom
version: 5.16
lessThanOrEqual: *
status: unaffected
versionType: original_commit_for_fix
title: nfsd: Fix nsfd startup race (again)
x_generator: engine: bippy-d175d3acf727