linux-kernel - Re: [PATCH] UDPCP Communication Protocol

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: <1293794758.2973.49.camel@edumazet-laptop>
Date:	Fri, 31 Dec 2010 12:25:58 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	stefani@...bold.net
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] UDPCP Communication Protocol

Le vendredi 31 décembre 2010 à 10:29 +0100, stefani@...bold.net a
écrit :
> +		if (!list_empty(&usk->destlist)) {
> +			state->sk = (struct sock *)usk;
> +			state->dest = list_first_entry(&usk->destlist,
> +					struct udpcp_dest, list);
> +			sock_hold(state->sk);
> +
> +			if (atomic_read(&state->sk->sk_refcnt) != 1) {
> +				spin_unlock_irqrestore(&spinlock, flags);
> +				return state;
> +			}
> +			atomic_dec(&state->sk->sk_refcnt);
> +		}
> +

I am trying to understand what you are doing here.

It seems racy to me.

Apparently, what you want is to take a reference only if actual
sk_refcnt is not zero.

I suggest using atomic_inc_notzero(&state->sk->sk_refcnt) to avoid the
race in atomic_dec().



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/