linux-kernel - [PATCH] ALSA: xen: ensure nul-terminated device name

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Message-Id: <20180528160011.2989632-1-arnd@arndb.de>
Date:   Mon, 28 May 2018 17:59:57 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
Cc:     Arnd Bergmann <arnd@...db.de>, xen-devel@...ts.xenproject.org,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ALSA: xen: ensure nul-terminated device name

gcc-8 warns that pcm_instance->name is not necessarily terminated correctly
if the input is more than 80 characters long or lacks a termination byte
itself:

In function 'strncpy',
    inlined from 'cfg_device' at sound/xen/xen_snd_front_cfg.c:399:3,
    inlined from 'xen_snd_front_cfg_card' at sound/xen/xen_snd_front_cfg.c:509:9:
include/linux/string.h:254:9: error: '__builtin_strncpy' specified bound 80 equals destination size [-Werror=stringop-truncation]
  return __builtin_strncpy(p, q, size);

Using strlcpy() instead of strncpy() makes this a bit safer.

Fixes: fd3b36045c2c ("ALSA: xen-front: Read sound driver configuration from Xen store")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 sound/xen/xen_snd_front_cfg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/xen/xen_snd_front_cfg.c b/sound/xen/xen_snd_front_cfg.c
index 38c7e1eefbb9..684b5f1d51ac 100644
--- a/sound/xen/xen_snd_front_cfg.c
+++ b/sound/xen/xen_snd_front_cfg.c
@@ -396,7 +396,7 @@ static int cfg_device(struct xen_snd_front_info *front_info,
 
 	str = xenbus_read(XBT_NIL, device_path, XENSND_FIELD_DEVICE_NAME, NULL);
 	if (!IS_ERR(str)) {
-		strncpy(pcm_instance->name, str, sizeof(pcm_instance->name));
+		strlcpy(pcm_instance->name, str, sizeof(pcm_instance->name));
 		kfree(str);
 	}
 
-- 
2.9.0