[ovs-dev] [reordering 1/7] ofproto-dpif: Fix use-after-free error deleting last bridge.

[Jarno Rajahalme]

Acked-by: Jarno Rajahalme <jrajahalme at nicira.com>

On Sep 16, 2013, at 2:59 PM, Ben Pfaff <blp at nicira.com> wrote:

> valgrind reported:
> 
>    Invalid read of size 4
>       at 0x806ADC1: odp_port_to_ofport (hmap.h:267)
>       by 0x8077C05: xlate_receive (ofproto-dpif-xlate.c:523)
>       by 0x8073994: handle_miss_upcalls (ofproto-dpif-upcall.c:642)
>       by 0x80741AA: udpif_miss_handler (ofproto-dpif-upcall.c:412)
>       by 0x56FCC38: start_thread (pthread_create.c:304)
>       by 0x735378D: clone (clone.S:130)
>     Address 0x786c084 is 4 bytes inside a block of size 16 free'd
>       at 0x4D8350C: free (vg_replace_malloc.c:427)
>       by 0x8065EDA: close_dpif_backer (ofproto-dpif.c:1094)
> 
> The problem is that close_dpif_backer() destroys odp_to_ofport_map and the
> associated mutex before it calls udpif_destroy() to stop the forwarding
> threads.  This gives the forwarding threads a window in which to try to
> use odp_to_ofport_map.
> 
> This commit moves the udpif_destroy() call much earlier, solving the
> problem.  (The call to udpif_destroy() must follow the call to
> drop_key_clear() because drop_key_clear() uses the udpif.)
> 
> Signed-off-by: Ben Pfaff <blp at nicira.com>
> ---
> ofproto/ofproto-dpif.c |    3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
> index b91b3df..b41c179 100644
> --- a/ofproto/ofproto-dpif.c
> +++ b/ofproto/ofproto-dpif.c
> @@ -1090,13 +1090,14 @@ close_dpif_backer(struct dpif_backer *backer)
>     drop_key_clear(backer);
>     hmap_destroy(&backer->drop_keys);
> 
> +    udpif_destroy(backer->udpif);
> +
>     simap_destroy(&backer->tnl_backers);
>     ovs_rwlock_destroy(&backer->odp_to_ofport_lock);
>     hmap_destroy(&backer->odp_to_ofport_map);
>     node = shash_find(&all_dpif_backers, backer->type);
>     free(backer->type);
>     shash_delete(&all_dpif_backers, node);
> -    udpif_destroy(backer->udpif);
>     dpif_close(backer->dpif);
> 
>     ovs_assert(hmap_is_empty(&backer->subfacets));
> -- 
> 1.7.10.4
> 
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