Re: [PATCH] net/rds: Fix a use after free in rds_message_map_pages

[David Miller <davem@xxxxxxxxxxxxx>]

From: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
Date: Tue, 30 Mar 2021 03:16:02 -0700

> @@ -348,7 +348,7 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in
>  	rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs);
>  	if (IS_ERR(rm->data.op_sg)) {
>  		rds_message_put(rm);
> -		return ERR_CAST(rm->data.op_sg);
> +		return ERR_PTR(-ENOMEM);
>  	}
>  
>  	for (i = 0; i < rm->data.op_nents; ++i) {

Maybe instead do:

      int err = ERR_CAST(rm->data.op_sg);
      rds_message_put(rm);
      return err;

Then if rds_message_alloc_sgs() starts to return other errors, they will propagate.

Thank you.