linux-kernel - Re: [PATCH] net: fix multithreaded signal handling in unix recv routines

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] [day] [month] [year] [list]

Message-Id: <20110307.153137.212682178.davem@davemloft.net>
Date:	Mon, 07 Mar 2011 15:31:37 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	rweikusat@...ileactivedefense.com
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: fix multithreaded signal handling in unix recv
 routines

From: Rainer Weikusat <rweikusat@...ileactivedefense.com>
Date: Mon, 28 Feb 2011 14:50:55 +0000

> From: Rainer Weikusat <rweikusat@...ileactivedefense.com>
> 
> The unix_dgram_recvmsg and unix_stream_recvmsg routines in
> net/af_unix.c utilize mutex_lock(&u->readlock) calls in order to
> serialize read operations of multiple threads on a single socket. This
> implies that, if all n threads of a process block in an AF_UNIX recv
> call trying to read data from the same socket, one of these threads
> will be sleeping in state TASK_INTERRUPTIBLE and all others in state
> TASK_UNINTERRUPTIBLE. Provided that a particular signal is supposed to
> be handled by a signal handler defined by the process and that none of
> this threads is blocking the signal, the complete_signal routine in
> kernel/signal.c will select the 'first' such thread it happens to
> encounter when deciding which thread to notify that a signal is
> supposed to be handled and if this is one of the TASK_UNINTERRUPTIBLE
> threads, the signal won't be handled until the one thread not blocking
> on the u->readlock mutex is woken up because some data to process has
> arrived (if this ever happens). The included patch fixes this by
> changing mutex_lock to mutex_lock_interruptible and handling possible
> error returns in the same way interruptions are handled by the actual
> receive-code.
> 
> Signed-off-by: Rainer Weikusat <rweikusat@...ileactivedefense.com>

Looks good, applied, thanks.
--
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/