netdev - Re: [PATCH net] net: sctp: fix smatch warning in sctp_send_asconf_del

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <B8C81C0E-1D13-40A9-A39F-4E5C8069366D@sfc.wide.ad.jp>
Date:	Sat, 7 Sep 2013 21:40:15 +0200
From:	Michio Honda <micchie@....wide.ad.jp>
To:	Daniel Borkmann <dborkman@...hat.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	linux-sctp@...r.kernel.org, Neil Horman <nhorman@...driver.com>
Subject: Re: [PATCH net] net: sctp: fix smatch warning in sctp_send_asconf_del_ip

Hi, 

Sorry for that I didn't respond to that warning.
You are right, laddr == NULL && addrcnt == 1 is the indicator of the function called by
asconf_mgmt().

Since your patch is actually redundant, I would suggest putting comment on the 
line of "if ((laddr == NULL) && (addrcnt == 1)) {", and/or on the checking in your patch.

Cheers,
- Michio
 
On Sep 7, 2013, at 8:51 PM, Daniel Borkmann wrote:

> This was originally reported in [1] and posted by Neil Horman [2], he said:
> 
>  Fix up a missed null pointer check in the asconf code. If we don't find
>  a local address, but we pass in an address length of more than 1, we may
>  dereference a NULL laddr pointer. Currently this can't happen, as the only
>  users of the function pass in the value 1 as the addrcnt parameter, but
>  its not hot path, and it doesn't hurt to check for NULL should that ever
>  be the case.
> 
> The callpath from sctp_asconf_mgmt() looks okay. But this could be triggered
> from sctp_setsockopt_bindx() call with SCTP_BINDX_REM_ADDR and addrcnt > 1
> while passing all possible addresses from the bind list to SCTP_BINDX_REM_ADDR
> so that we do *not* find a single address in the association's bind address
> list that is not in the packed array of addresses. If this happens when we
> have an established association with ASCONF-capable peers, then we could get
> a NULL pointer dereference as we only check for laddr == NULL && addrcnt == 1
> and call later sctp_make_asconf_update_ip() with NULL laddr.
> 
> BUT: this actually won't happen as sctp_bindx_rem() will catch such a case
> and return with an error earlier. As this is incredably unintuitive and error
> prone, add a check to catch at least future bugs here. As Neil says, its not
> hot path. Introduced by 8a07eb0a5 ("sctp: Add ASCONF operation on the
> single-homed host").
> 
> [1] http://www.spinics.net/lists/linux-sctp/msg02132.html
> [2] http://www.spinics.net/lists/linux-sctp/msg02133.html
> 
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Neil Horman <nhorman@...driver.com>
> Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
> Cc: Michio Honda <micchie@....wide.ad.jp>
> ---
> net/sctp/socket.c | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 5462bbb..911b71b 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -806,6 +806,9 @@ static int sctp_send_asconf_del_ip(struct sock		*sk,
> 			goto skip_mkasconf;
> 		}
> 
> +		if (laddr == NULL)
> +			return -EINVAL;
> +
> 		/* We do not need RCU protection throughout this loop
> 		 * because this is done under a socket lock from the
> 		 * setsockopt call.
> -- 
> 1.7.11.7
> 

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html