Patchwork sctp: proc: protect bind_addr->address_list accesses with rcu_read_lock()

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Submitter Thomas Graf
Date Dec. 6, 2012, 5:34 p.m.
Message ID <a803093c70e857e8e01e554288ee79f66f7acda4.1354814846.git.tgraf@suug.ch>
Download mbox | patch
Permalink /patch/204291/
State Changes Requested
Delegated to: David Miller
Headers show

Comments

Thomas Graf - Dec. 6, 2012, 5:34 p.m.
address_list is protected via the socket lock or RCU. Since we don't want
to take the socket lock for each assoc we dump in procfs a RCU read-side
critical section must be entered.

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
---
 net/sctp/proc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
Vlad Yasevich - Dec. 6, 2012, 6:25 p.m.
On 12/06/2012 12:34 PM, Thomas Graf wrote:
> address_list is protected via the socket lock or RCU. Since we don't want
> to take the socket lock for each assoc we dump in procfs a RCU read-side
> critical section must be entered.
>
> Cc: Vlad Yasevich <vyasevich@gmail.com>
> Cc: Neil Horman <nhorman@tuxdriver.com>
> Signed-off-by: Thomas Graf <tgraf@suug.ch>
> ---
>   net/sctp/proc.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/sctp/proc.c b/net/sctp/proc.c
> index 9966e7b..ec9b0c8 100644
> --- a/net/sctp/proc.c
> +++ b/net/sctp/proc.c
> @@ -139,7 +139,8 @@ static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
>   	    primary = &peer->saddr;
>   	}
>
> -	list_for_each_entry(laddr, &epb->bind_addr.address_list, list) {
> +	rcu_read_lock();
> +	list_for_each_entry_rcu(laddr, &epb->bind_addr.address_list, list) {
>   		addr = &laddr->a;
>   		af = sctp_get_af_specific(addr->sa.sa_family);
>   		if (primary && af->cmp_addr(addr, primary)) {
> @@ -147,6 +148,7 @@ static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
>   		}
>   		af->seq_dump_addr(seq, addr);
>   	}
> +	rcu_read_unlock();
>   }
>
>   /* Dump remote addresses of an association. */
>

May want to avoid printing addresses that are !addr->valid.

Otherwise looks good.

-vlad
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Thomas Graf - Dec. 6, 2012, 6:28 p.m.
On 12/06/12 at 01:25pm, Vlad Yasevich wrote:
> May want to avoid printing addresses that are !addr->valid.
> 
> Otherwise looks good.

Good point, I'll send a follow-up patch if that is OK. Same
applies to dead transports obviously.
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Neil Horman - Dec. 6, 2012, 7:16 p.m.
On Thu, Dec 06, 2012 at 06:28:40PM +0000, Thomas Graf wrote:
> On 12/06/12 at 01:25pm, Vlad Yasevich wrote:
> > May want to avoid printing addresses that are !addr->valid.
> > 
> > Otherwise looks good.
> 
> Good point, I'll send a follow-up patch if that is OK. Same
> applies to dead transports obviously.
Assuming a followup patch to avoid dead addresses..
Acked-by: Neil Horman <nhorman@tuxdriver.com>

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Patch

diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index 9966e7b..ec9b0c8 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -139,7 +139,8 @@  static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
 	    primary = &peer->saddr;
 	}
 
-	list_for_each_entry(laddr, &epb->bind_addr.address_list, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(laddr, &epb->bind_addr.address_list, list) {
 		addr = &laddr->a;
 		af = sctp_get_af_specific(addr->sa.sa_family);
 		if (primary && af->cmp_addr(addr, primary)) {
@@ -147,6 +148,7 @@  static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
 		}
 		af->seq_dump_addr(seq, addr);
 	}
+	rcu_read_unlock();
 }
 
 /* Dump remote addresses of an association. */