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NFS: Use parent's objective cred in nfs_access_login_time()

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[ Upstream commit a10a9233073d984b239e22358ba21825e27e2e88 ]

The subjective cred (task->cred) can potentially be overridden and
subsquently freed in non-RCU context, which could lead to a panic if we
try to use it in cred_fscmp().  Use __task_cred(), which returns the
objective cred (task->real_cred) instead.

Fixes: 0eb43812c027 ("NFS: Clear the file access cache upon login")
Fixes: 5e9a7b9c2ea1 ("NFS: Fix up a sparse warning")

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Scott Mayhew 2023-12-05 09:10:54 -05:00 committed by Greg Kroah-Hartman
parent b4b7dd1cb6
commit 4ffac00134
1 changed files with 1 additions and 1 deletions

2
fs/nfs/dir.c

@ -2968,7 +2968,7 @@ static u64 nfs_access_login_time(const struct task_struct *task,
rcu_read_lock();
for (;;) {
parent = rcu_dereference(task->real_parent);
pcred = rcu_dereference(parent->cred);
pcred = __task_cred(parent);
if (parent == task || cred_fscmp(pcred, cred) != 0)
break;
task = parent;