From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: ACJfBovJVBOdyXUjYlGngWsDrvSp9W3Vt/vuwsXrjWvtw0B+JKErK8Xpfr6/4EmnX3ou9B4LVcBp ARC-Seal: i=1; a=rsa-sha256; t=1516375800; cv=none; d=google.com; s=arc-20160816; b=iePBxm5Q0v7wijKYsmevBQIIqpt+QhaUp0C5TJFLX6y2nzPOXE72pD3d0G8WX8Smw2 5hMgz1J/05/qp8R91vPihGMpgW+zZ8xFCYerpHI0eKZIpgfm3+5nXqzPdDgNP7WOVj9F 7f6ZXrRYO8fArvhzbVHmbd2xFWU76Lz/eHrBEhWvDILeU5uGWx18ta502mv1MaGUzlc5 ePzEX9DU9gh9w00oknLN9VmToINgCdg+quLGGrrTJp/LXGvQj3Bs8mV0hBC/FfkfaDEG wJp3GAwnquL3X1WdWQN7MjBBdnSfYrtTt0zgFsW1dOdkPcXbXJ2dImJOryfjM3DlkfP3 m15A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :arc-authentication-results; bh=aoc4CEYMtxTABXN1SYtHAK3mOjOsZllmRW7oEROSsqA=; b=C00hxw/jjFp2IcvBsY4ZjFqaC5Q9KCFpk0eegqPKuaQUU61LbTZNEZ7KbOPR3YOEnv rS3yVUpgPxeUYi45yefhP0vC64QJWlVR2a1WDZp3Udnwt+q//C9HRb8cLD+dWKusobmr nNGCJP2I4zd4v7gWdPSiao6vTfI2vuFHPjynMGUmvHJUotzD60dlrOZ7Jxs5S2tDssgi bVixlpzWqnAUYeMYsGHt3Kty+5KK7OhrsB5ICP0Hjb/ss9iUIiF8pv+HztjYYvmz8bi6 tctX4JYpIErdDbv7Qh0Ls3Kr/YOKGDDmAH8E0vDXVIYcn9rHkIaYynCpCigqDb4FUhW5 Kbrg== ARC-Authentication-Results: i=1; mx.google.com; spf=neutral (google.com: 2a02:1800:110:4::f00:19 is neither permitted nor denied by best guess record for domain of geert@linux-m68k.org) smtp.mailfrom=geert@linux-m68k.org Authentication-Results: mx.google.com; spf=neutral (google.com: 2a02:1800:110:4::f00:19 is neither permitted nor denied by best guess record for domain of geert@linux-m68k.org) smtp.mailfrom=geert@linux-m68k.org From: Geert Uytterhoeven To: Russell King Cc: Antonios Motakis , Adrian Salido , Sasha Levin , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH 2/4] ARM: amba: Fix race condition with driver_override Date: Fri, 19 Jan 2018 16:24:08 +0100 Message-Id: <1516375450-30575-3-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1516375450-30575-1-git-send-email-geert+renesas@glider.be> References: <1516375450-30575-1-git-send-email-geert+renesas@glider.be> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590035271769830426?= X-GMAIL-MSGID: =?utf-8?q?1590035271769830426?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: The driver_override implementation is susceptible to a race condition when different threads are reading vs storing a different driver override. Add locking to avoid this race condition. Cfr. commits 6265539776a0810b ("driver core: platform: fix race condition with driver_override") and 9561475db680f714 ("PCI: Fix race condition with driver_override"). Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'") Signed-off-by: Geert Uytterhoeven --- drivers/amba/bus.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 6ffd778352e6d953..36c5653ced5742b7 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -69,8 +69,12 @@ static ssize_t driver_override_show(struct device *_dev, struct device_attribute *attr, char *buf) { struct amba_device *dev = to_amba_device(_dev); + ssize_t len; - return sprintf(buf, "%s\n", dev->driver_override); + device_lock(_dev); + len = sprintf(buf, "%s\n", dev->driver_override); + device_unlock(_dev); + return len; } static ssize_t driver_override_store(struct device *_dev, @@ -78,7 +82,7 @@ static ssize_t driver_override_store(struct device *_dev, const char *buf, size_t count) { struct amba_device *dev = to_amba_device(_dev); - char *driver_override, *old = dev->driver_override, *cp; + char *driver_override, *old, *cp; if (count > PATH_MAX) return -EINVAL; @@ -91,12 +95,15 @@ static ssize_t driver_override_store(struct device *_dev, if (cp) *cp = '\0'; + device_lock(_dev); + old = dev->driver_override; if (strlen(driver_override)) { dev->driver_override = driver_override; } else { kfree(driver_override); dev->driver_override = NULL; } + device_unlock(_dev); kfree(old); -- 2.7.4