From fa06883281afaa158b2b350f16c377c448df6b61 Mon Sep 17 00:00:00 2001 From: Chris Leech Date: Thu, 30 Jun 2016 08:32:36 -0700 Subject: [PATCH] libfc: sanity check cpu number extracted from xid In the receive path libfc extracts a cpu number from the ox_id in the fiber channel header and uses that to do a per_cpu_ptr conversion. If, for some reason, a frame is received with an invalid ox_id, per_cpu_ptr will return an invalid pointer and the libfc receive path will panic the system trying to use it. I'm currently looking at such a case, and I don't yet know why a cpu number > nr_cpu_ids is appearing in an exchange id. But adding a sanity check in libfc prevents a system panic, and seems like good idea when dealing with frames coming in from the network. Signed-off-by: Chris Leech Acked-by: Johannes Thumshirn Signed-off-by: Martin K. Petersen --- drivers/scsi/libfc/fc_exch.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c index 30f9ef0c0d4f..e72673b0a8fb 100644 --- a/drivers/scsi/libfc/fc_exch.c +++ b/drivers/scsi/libfc/fc_exch.c @@ -908,9 +908,17 @@ static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid) { struct fc_exch_pool *pool; struct fc_exch *ep = NULL; + u16 cpu = xid & fc_cpu_mask; + + if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) { + printk_ratelimited(KERN_ERR + "libfc: lookup request for XID = %d, " + "indicates invalid CPU %d\n", xid, cpu); + return NULL; + } if ((xid >= mp->min_xid) && (xid <= mp->max_xid)) { - pool = per_cpu_ptr(mp->pool, xid & fc_cpu_mask); + pool = per_cpu_ptr(mp->pool, cpu); spin_lock_bh(&pool->lock); ep = fc_exch_ptr_get(pool, (xid - mp->min_xid) >> fc_cpu_order); if (ep) {