Re: [PATCH rdma-cm] IB/core: Fix memory corruption in ib_cache_gid_set_default_gid

[Doug Ledford]

On 10/15/2015 08:01 AM, Matan Barak wrote:
> From: Doron Tsur <dor...@mellanox.com>
> 
> When ib_cache_gid_set_default_gid is called from several threads,
> updating the table could make find_gid fail, therefore a negative
> index will be retruned and an invalid table entry will be used.
> Locking find_gid as well fixes this problem.
> 
> Fixes: 03db3a2d81e6 ('IB/core: Add RoCE GID table management')
> Signed-off-by: Doron Tsur <dor...@mellanox.com>
> Signed-off-by: Matan Barak <mat...@mellanox.com>
> ---
> 
> Hi Doug,
> 
> This patch fixes a bug in RoCE GID table implementation. When several
> instances executes ib_cache_gid_set_default_gid, we could try to update
> the same default GID (at the same index) simultaneously.
> Therefore, find_gid will fail finding this default GID and we'll hit the
> WARN_ON condition.
> 
> We hit this bug while testing this code under pressure of doing ifup/ifdown.
> 
> Thanks,
> Matan

Safe enough, applied for rc.

> 
>  drivers/infiniband/core/cache.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
> index 8f66c67..87471ef 100644
> --- a/drivers/infiniband/core/cache.c
> +++ b/drivers/infiniband/core/cache.c
> @@ -508,12 +508,12 @@ void ib_cache_gid_set_default_gid(struct ib_device 
> *ib_dev, u8 port,
>       memset(&gid_attr, 0, sizeof(gid_attr));
>       gid_attr.ndev = ndev;
>  
> +     mutex_lock(&table->lock);
>       ix = find_gid(table, NULL, NULL, true, GID_ATTR_FIND_MASK_DEFAULT);
>  
>       /* Coudn't find default GID location */
>       WARN_ON(ix < 0);
>  
> -     mutex_lock(&table->lock);
>       if (!__ib_cache_gid_get(ib_dev, port, ix,
>                               &current_gid, &current_gid_attr) &&
>           mode == IB_CACHE_GID_DEFAULT_MODE_SET &&
> 


-- 
Doug Ledford <dledf...@redhat.com>
              GPG KeyID: 0E572FDD

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