Commit 2f6fc056 authored by J. Bruce Fields's avatar 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: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 0f1738a1
...@@ -876,6 +876,7 @@ nfsd4_secinfo(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, ...@@ -876,6 +876,7 @@ nfsd4_secinfo(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
&exp, &dentry); &exp, &dentry);
if (err) if (err)
return err; return err;
fh_unlock(&cstate->current_fh);
if (d_really_is_negative(dentry)) { if (d_really_is_negative(dentry)) {
exp_put(exp); exp_put(exp);
err = nfserr_noent; err = nfserr_noent;
......
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