From 4ffac0013421295e055005e8ae47d8c5b8ada387 Mon Sep 17 00:00:00 2001 From: Scott Mayhew Date: Tue, 5 Dec 2023 09:10:54 -0500 Subject: [PATCH] NFS: Use parent's objective cred in nfs_access_login_time() [ 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 Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin --- fs/nfs/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index e6a51fd..9fc5061 100644 --- a/fs/nfs/dir.c +++ b/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; -- 2.7.4