On Thu, Jun 30, 2016 at 08:32:36AM -0700, Chris Leech wrote:
> 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 <cleech@xxxxxxxxxx>
> ---
> 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 30f9ef0..e72673b 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) {
Acked-by: Johannes Thumshirn <jth@xxxxxxxxxx>
@Martin, do you queue the libfc patches as well?
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Johannes Thumshirn Storage
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