linux-kernel - [PATCH V2 1/3] RAS, mce_amd_inj: Return early on invalid input

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Date:	Fri, 25 Sep 2015 09:20:49 -0500
From:	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
To:	<bp@...e.de>, <tglx@...utronix.de>, <mingo@...hat.com>,
	<hpa@...or.com>
CC:	<x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
Subject: [PATCH V2 1/3] RAS, mce_amd_inj: Return early on invalid input

Invalid input such as these are currently reported on dmesg-
$> echo sweet > flags
[  122.079139] flags_write: Invalid flags value: et

Even if the 'flags' attribute has been updated correctly-
$> cat flags
sw

But the input as a whole is wrong and we should not be
writing anything to the file. Therefore, modifying the
behavior in this patch to return EINVAL on bad input strings

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
---
 arch/x86/ras/mce_amd_inj.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/ras/mce_amd_inj.c b/arch/x86/ras/mce_amd_inj.c
index 17e35b5..4fd8bb9 100644
--- a/arch/x86/ras/mce_amd_inj.c
+++ b/arch/x86/ras/mce_amd_inj.c
@@ -129,12 +129,9 @@ static ssize_t flags_write(struct file *filp, const char __user *ubuf,
 {
 	char buf[MAX_FLAG_OPT_SIZE], *__buf;
 	int err;
-	size_t ret;
 
 	if (cnt > MAX_FLAG_OPT_SIZE)
-		cnt = MAX_FLAG_OPT_SIZE;
-
-	ret = cnt;
+		return -EINVAL;
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
@@ -150,9 +147,9 @@ static ssize_t flags_write(struct file *filp, const char __user *ubuf,
 		return err;
 	}
 
-	*ppos += ret;
+	*ppos += cnt;
 
-	return ret;
+	return cnt;
 }
 
 static const struct file_operations flags_fops = {
-- 
2.4.0

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