From: Greg Kroah-Hartman <gregkh@suse.de>
Date: Tue, 20 Jan 2009 23:51:16 +0000 (-0800)
Subject: sysfs: fix problems with binary files
X-Git-Tag: v2.6.27.14~27
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2085509e2715178a54cf23dc63f87cb2c58f3bf4;p=thirdparty%2Fkernel%2Fstable.git

sysfs: fix problems with binary files

commit 4503efd0891c40e30928afb4b23dc3f99c62a6b2 upstream.

Some sysfs binary files don't like having 0 passed to them as a size.
Fix this up at the root by just returning to the vfs if userspace asks
us for a zero sized buffer.

Thanks to Pavel Roskin for pointing this out.

Reported-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 006fc64227ddb..aa244842f30b7 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -62,6 +62,9 @@ read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
 	loff_t offs = *off;
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 
+	if (!bytes)
+		return 0;
+
 	if (size) {
 		if (offs > size)
 			return 0;
@@ -119,6 +122,9 @@ static ssize_t write(struct file *file, const char __user *userbuf,
 	loff_t offs = *off;
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 
+	if (!bytes)
+		return 0;
+
 	if (size) {
 		if (offs > size)
 			return 0;