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

[David Miller]

From: Lv Yunlong <lyl2...@mail.ustc.edu.cn>
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.