linux-kernel - [PATCH v2 2/2] sound: dummy, avoid race with timer

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]

Date:	Mon, 19 Jan 2015 10:56:41 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	tiwai@...e.de
Cc:	linux-kernel@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
	Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org
Subject: [PATCH v2 2/2] sound: dummy, avoid race with timer

There is a race between timer and process contexts. Process context
does not disable irqs, so when a timer ticks inside process' critical
section, the system can deadlock. Fix this by a traditional _irqsave
variant of spin_lock.

[v2] removed ->pointer change as it is called with BH off

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Jaroslav Kysela <perex@...ex.cz>
Cc: Takashi Iwai <tiwai@...e.de>
Cc: alsa-devel@...a-project.org
---
 sound/drivers/dummy.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index d11baaf0f0b4..0791210cb4e7 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -271,10 +271,13 @@ static void dummy_systimer_update(struct dummy_systimer_pcm *dpcm)
 static int dummy_systimer_start(struct snd_pcm_substream *substream)
 {
 	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
-	spin_lock(&dpcm->lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dpcm->lock, flags);
 	dpcm->base_time = jiffies;
 	dummy_systimer_rearm(dpcm);
-	spin_unlock(&dpcm->lock);
+	spin_unlock_irqrestore(&dpcm->lock, flags);
+
 	return 0;
 }
 
-- 
2.2.1

--
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/