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Subject[PATCH] Fix suspicious RCU usage in nfs_idmap_get_key.
Date
nfs_idmap_get_key doesn't hold rkey->sem when calling user_key_payload
resulting in a "suspicious RCU usage" lockdep splat. It does, however hold
rcu_read_lock, so it either needs to use unprotected rcu_dereference, or take
rkey->sem instead of rcu_read_lock.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
fs/nfs/nfs4idmap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4idmap.c b/fs/nfs/nfs4idmap.c
index c444285..a67d1c0 100644
--- a/fs/nfs/nfs4idmap.c
+++ b/fs/nfs/nfs4idmap.c
@@ -309,7 +309,7 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
goto out;
}

- rcu_read_lock();
+ down_read(&rkey->sem);
rkey->perm |= KEY_USR_VIEW;

ret = key_validate(rkey);
@@ -329,7 +329,7 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
ret = -EINVAL;

out_up:
- rcu_read_unlock();
+ up_read(&rkey->sem);
key_put(rkey);
out:
return ret;
--
2.7.4
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