tree f6327b45df075955d8ef9e9ad93c453ea5fc7a4c
parent ccecee1e5e42981f5eb37f4411e8552b9db04d30
author J. Bruce Fields <bfields@citi.umich.edu> 1241564669 -0400
committer J. Bruce Fields <bfields@citi.umich.edu> 1241640996 -0400

nfsd4: check for negative dentry before use in nfsv4 readdir

After 2f9092e1020246168b1309b35e085ecd7ff9ff72 "Fix i_mutex vs.  readdir
handling in nfsd" (and 14f7dd63 "Copy XFS readdir hack into nfsd code"),
an entry may be removed between the first mutex_unlock and the second
mutex_lock. In this case, lookup_one_len() will return a negative
dentry.  Check for this case to avoid a NULL dereference.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Reviewed-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Cc: stable@kernel.org