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From: Sowmini Varadhan <sowmini.varadhan@oracle•com>
To: Santosh Shilimkar <santosh.shilimkar@oracle•com>
Cc: netdev@vger•kernel.org, davem@davemloft•net
Subject: Re: [PATCH] rds: fix use-after-free read in rds_find_bound
Date: Sat, 30 Dec 2017 15:26:31 -0500	[thread overview]
Message-ID: <20171230202631.GB27855@oracle.com> (raw)
In-Reply-To: <1514662599-14491-1-git-send-email-santosh.shilimkar@oracle.com>

On (12/30/17 11:36), Santosh Shilimkar wrote:
> 
> socket buffer can get freed as part of sock_close
> callback so before adding reference check underneath
> socket validity.

I'm not sure I understand this fix-  

struct rds_sock is:
  struct rds_sock {
        struct sock             rs_sk;
         :
  }

How can  rs be non-null but rds_rs_to_sk() is null? (Note that
rds_rs_to_sk just returns &rs->rs_sk) so the changed line is 
identical to the original line.

> -	if (rs && !sock_flag(rds_rs_to_sk(rs), SOCK_DEAD))
> +	if (rs && rds_rs_to_sk(rs) && !sock_flag(rds_rs_to_sk(rs), SOCK_DEAD))

I think the real issue is refcount bug somewhere,

Was the syzbot test run with http://patchwork.ozlabs.org/patch/852492/
this sounds like that type of bug.

--Sowmini

  reply	other threads:[~2017-12-30 20:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-30 19:36 [PATCH] rds: fix use-after-free read in rds_find_bound Santosh Shilimkar
2017-12-30 20:26 ` Sowmini Varadhan [this message]
2017-12-30 21:37   ` santosh.shilimkar
2017-12-30 22:32     ` Sowmini Varadhan
2017-12-31  5:09       ` santosh.shilimkar
2017-12-31 12:33         ` Sowmini Varadhan
2017-12-31 22:30           ` santosh.shilimkar

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