[ovs-dev] [PATCH 1/4] ofproto-dpif-xlate: Fix bad memory free.

Ben Pfaff blp at ovn.org
Mon Oct 30 19:39:25 UTC 2017


On Mon, Oct 30, 2017 at 10:27:52AM -0700, William Tu wrote:
> Clang reports possibly bad free of 'ofm' when it comes from the stack
> instead of malloc because Clang is not able to verify whether the previous
> if condition 'ctx->xin->xcache' still hold the same.  Fix it by
> adding additional condition.
> 
> Signed-off-by: William Tu <u9012063 at gmail.com>
> ---
>  ofproto/ofproto-dpif-xlate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index ddcaf059ded2..b8a4986061a9 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -5128,7 +5128,7 @@ xlate_learn_action(struct xlate_ctx *ctx, const struct ofpact_learn *learn)
>              }
>          }
>  
> -        if (ctx->xin->xcache) {
> +        if (ctx->xin->xcache && ofm != &ofm__) {
>              free(ofm);
>          }

Hmm, this is interesting.  Can we just change this to:
        if (ofm != &ofm__)
though?  (free(NULL) is harmless.)

Thanks,

Ben.


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