Commit 2f6fc056 authored Mar 02, 2016 by J. Bruce Fields

nfsd: fix deadlock secinfo+readdir compound



nfsd_lookup_dentry exits with the parent filehandle locked.  fh_put also
unlocks if necessary (nfsd filehandle locking is probably too lenient),
so it gets unlocked eventually, but if the following op in the compound
needs to lock it again, we can deadlock.

A fuzzer ran into this; normal clients don't send a secinfo followed by
a readdir in the same compound.

Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

parent 0f1738a1

fs/nfsd/nfs4proc.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -876,6 +876,7 @@ nfsd4_secinfo(struct svc_rqst rqstp, struct nfsd4_compound_state cstate,
		&exp, &dentry);
		if (err)
		return err;
		fh_unlock(&cstate->current_fh);
		if (d_really_is_negative(dentry)) {
		exp_put(exp);
		err = nfserr_noent;

Admin message