From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx48iue6kissDR059OdVnnp+XZNJHfwu9nTakNTnqA0hiN9nWwIhIn3zl05egRLdrE5y595xA ARC-Seal: i=1; a=rsa-sha256; t=1523366514; cv=none; d=google.com; s=arc-20160816; b=pFga49i8+NtoZBvuYrZeTYNVDtcXjje0FHUWTj6oxTPaeQ3jVDpV23JwbGg8u2wX6c tt6iv/6frgqlZzkKVrDLDxYJlzbHWoLJa9W1yh69nmh/X+u3O6InPXaws5on13ijw1uN 2dD2SHeQl1qXWDx4AOOBq1GMHwvbQcOLcMzqP224bdLtNTVmlBI8yYjbc8PUcVMjhDiZ jz3FT5/BRYx2LUc3tpE7Pr2wkPUFe4xDPw91yubM1WEovnw1bKfiZiJ6SeHPb9qsfN+z xqN5L+A4viTNS5zb3z8fVWpRbLEJHAd0wfoEH/R+PSZJh6sFAGjzsdfkhfqh1x+6IJBa 0EUw== 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=fjhrnOyv/+2G9+s04+SkJTlfZ3SYv5Tw4q2xtXZlS4dltVzRy537WesxYSuCU6+O06 4/gZcKkpj6BR33KexInyZWChQ2IGvl5VSXO0wLaSWNqwwr0ztbKNXyqgc6QMx9CR123S 0G4RGHcYf74K3pTB3vWLtHyHHD34dtKehIfFSYMAD2ZO+6Ci0aANC2EB+uqoc83ldVFP javmcRg8WDDQr/Db7vQb4mL5NR/F8k3iuYAVr4bojhYh6KalLtXgJhcyOrO4EUoqKi7T 85VToulHHS6PYBKsmbftjCxiS/Y3RvqBTxsgUK8ytX13/skZHfY93UEs33548zKfplLv amKw== ARC-Authentication-Results: i=1; mx.google.com; spf=neutral (google.com: 2a02:1800:120:4::f00:15 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: 2a02:1800:120:4::f00:15 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: Greg Kroah-Hartman Cc: Russell King , Adrian Salido , Nicolai Stange , Sasha Levin , Todd Kjos , linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH v2 2/4] ARM: amba: Fix race condition with driver_override Date: Tue, 10 Apr 2018 15:21:44 +0200 Message-Id: <1523366506-19832-3-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1523366506-19832-1-git-send-email-geert+renesas@glider.be> References: <1523366506-19832-1-git-send-email-geert+renesas@glider.be> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597365566189003865?= X-GMAIL-MSGID: =?utf-8?q?1597365566189003865?= 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