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Commit e09c978a authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4.1: Fix Oopsable condition in server callback races 



The slot table hasn't been an array since v3.7. Ensure that we
use nfs4_lookup_slot() to access the slot correctly.

Fixes: 87dda67e ("NFSv4.1: Allow SEQUENCE to resize the slot table...")
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v3.8+
parent 16590a22

fs/nfs/callback_proc.c

+1 −4
Original line number Diff line number Diff line
@@ -454,11 +454,8 @@ static bool referring_call_exists(struct nfs_client *clp, 
				((u32 *)&rclist->rcl_sessionid.data)[3],

				ref->rc_sequenceid, ref->rc_slotid);



			spin_lock(&tbl->slot_tbl_lock);

			status = (test_bit(ref->rc_slotid, tbl->used_slots) &&

				  tbl->slots[ref->rc_slotid].seq_nr ==

			status = nfs4_slot_seqid_in_use(tbl, ref->rc_slotid,

					ref->rc_sequenceid);

			spin_unlock(&tbl->slot_tbl_lock);

			if (status)

				goto out;

		}

fs/nfs/nfs4session.c

+33 −0
Original line number Diff line number Diff line
@@ -172,6 +172,39 @@ struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid) 
	return ERR_PTR(-E2BIG);

}



static int nfs4_slot_get_seqid(struct nfs4_slot_table  *tbl, u32 slotid,

		u32 *seq_nr)

	__must_hold(&tbl->slot_tbl_lock)

{

	struct nfs4_slot *slot;



	slot = nfs4_lookup_slot(tbl, slotid);

	if (IS_ERR(slot))

		return PTR_ERR(slot);

	*seq_nr = slot->seq_nr;

	return 0;

}



/*

 * nfs4_slot_seqid_in_use - test if a slot sequence id is still in use

 *

 * Given a slot table, slot id and sequence number, determine if the

 * RPC call in question is still in flight. This function is mainly

 * intended for use by the callback channel.

 */

bool nfs4_slot_seqid_in_use(struct nfs4_slot_table *tbl, u32 slotid, u32 seq_nr)

{

	u32 cur_seq;

	bool ret = false;



	spin_lock(&tbl->slot_tbl_lock);

	if (nfs4_slot_get_seqid(tbl, slotid, &cur_seq) == 0 &&

	    cur_seq == seq_nr && test_bit(slotid, tbl->used_slots))

		ret = true;

	spin_unlock(&tbl->slot_tbl_lock);

	return ret;

}



/*

 * nfs4_alloc_slot - efficiently look for a free slot

 *

fs/nfs/nfs4session.h

+1 −0
Original line number Diff line number Diff line
@@ -78,6 +78,7 @@ extern int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, 
extern void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl);

extern struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl);

extern struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid);

extern bool nfs4_slot_seqid_in_use(struct nfs4_slot_table  *tbl, u32 slotid, u32 seq_nr);

extern bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);

extern void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);

extern void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl);