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| author | Jann Horn <jannh@google.com> | 2026-08-06 22:15:54 +0200 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2026-08-31 16:14:09 -0400 |
| commit | b030ffaedc1d638f232f6992406cdcdcc82d5602 (patch) | |
| tree | 2802f24962af082633e86f5e86db43d7334e7d9c /init | |
| parent | cee9395acd8043be0644b25c34bfa86623f2b935 (diff) | |
| download | linux-next-b030ffaedc1d638f232f6992406cdcdcc82d5602.tar.gz linux-next-b030ffaedc1d638f232f6992406cdcdcc82d5602.zip | |
cred: clarify that task_struct::cred is only for the current task
The `cred` field in task_struct is currently marked as __rcu, but that's
not true: It can point to credentials from access_override_creds(), which
do not get freed with RCU delay.
What actually protects task_struct::cred is that accessing it is only
permitted for the current task (except for setting up a child during fork()
or tearing down a dead process).
(There is currently code in Smack that violates this rule, but that's a bug
and causes UAF, I have sent a separate fix for that.)
Clarify this, remove the __rcu marker, and remove RCU helpers from all
accesses to this field.
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
[PM: style tweak in security_init(), applied fixup from JH]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'init')
| -rw-r--r-- | init/init_task.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/init/init_task.c b/init/init_task.c index adb207cd987c..ce7c2b07d855 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -160,7 +160,7 @@ struct task_struct init_task __aligned(L1_CACHE_BYTES) = { .sibling = LIST_HEAD_INIT(init_task.sibling), .group_leader = &init_task, RCU_POINTER_INITIALIZER(real_cred, &init_cred), - RCU_POINTER_INITIALIZER(cred, &init_cred), + .cred = &init_cred, .comm = INIT_TASK_COMM, .thread = INIT_THREAD, .real_fs = &init_fs, |