linux-kernel - [PATCH 1/3] lightnvm: fix up nonsensical configure overrun checking

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Message-Id: <1455886619-3007-2-git-send-email-m@bjorling.me>
Date:	Fri, 19 Feb 2016 13:56:57 +0100
From:	Matias Bjørling <m@...rling.me>
To:	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
	axboe@...com
Cc:	Alan <gnomes@...rguk.ukuu.org.uk>, Alan Cox <alan@...ux.intel.com>,
	Matias Bjørling <m@...rling.me>
Subject: [PATCH 1/3] lightnvm: fix up nonsensical configure overrun checking

From: Alan <gnomes@...rguk.ukuu.org.uk>

Instead of checking a constant 0 actually check the space available. Even
better remember to allow for the header and also check the right amount of
space is needed.

Signed-off-by: Alan Cox <alan@...ux.intel.com>
Signed-off-by: Matias Bjørling <m@...rling.me>
---
 drivers/lightnvm/core.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index c3d4b54..b53632d 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -868,20 +868,19 @@ static int nvm_configure_by_str_event(const char *val,
 
 static int nvm_configure_get(char *buf, const struct kernel_param *kp)
 {
-	int sz = 0;
-	char *buf_start = buf;
+	int sz;
 	struct nvm_dev *dev;
 
-	buf += sprintf(buf, "available devices:\n");
+	sz = sprintf(buf, "available devices:\n");
 	down_write(&nvm_lock);
 	list_for_each_entry(dev, &nvm_devices, devices) {
-		if (sz > 4095 - DISK_NAME_LEN)
+		if (sz > 4095 - DISK_NAME_LEN - 2)
 			break;
-		buf += sprintf(buf, " %32s\n", dev->name);
+		sz += sprintf(buf + sz, " %32s\n", dev->name);
 	}
 	up_write(&nvm_lock);
 
-	return buf - buf_start - 1;
+	return sz;
 }
 
 static const struct kernel_param_ops nvm_configure_by_str_event_param_ops = {
-- 
2.1.4