linux-kernel - [PATCH] ALSA: pcm: retrieve true appl

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-next>] [day] [month] [year] [list]

Date:	12 Nov 2013 16:14:17 +0000
From:	"Oskar Schirmer" <oskar@...ra.com>
To:	"Jaroslav Kysela" <perex@...ex.cz>
Cc:	linux-kernel@...r.kernel.org, "Takashi Iwai" <tiwai@...e.de>,
	alsa-devel@...a-project.org,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Oskar Schirmer" <oskar@...ra.com>
Subject: [PATCH] ALSA: pcm: retrieve true appl_ptr where stream was unlocked

Calculated for data transfer, the local variable appl_ptr is reused,
changed and written back later, though the lock was not held during
the transfer earlier. Admitted, destiny of the lock is not obvious
at all, but this looks much like a race condition candidate, so make
sure to have some original appl_ptr value to work on.

Two occurences.

Signed-off-by: Oskar Schirmer <oskar@...ra.com>
---
 sound/core/pcm_lib.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 6e03b46..47e836a 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -2051,6 +2051,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
 		default:
 			break;
 		}
+		appl_ptr = runtime->control->appl_ptr;
 		appl_ptr += frames;
 		if (appl_ptr >= runtime->boundary)
 			appl_ptr -= runtime->boundary;
@@ -2283,6 +2284,7 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
 		default:
 			break;
 		}
+		appl_ptr = runtime->control->appl_ptr;
 		appl_ptr += frames;
 		if (appl_ptr >= runtime->boundary)
 			appl_ptr -= runtime->boundary;
-- 
1.7.9.5

--
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/