[patch 09/43] sysfs: fix problems with binary files

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Greg Kroah-Hartman <gregkh@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/sysfs/bin.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -63,6 +63,9 @@ read(struct file *file, char __user *use
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 	char *temp;
 
+	if (!bytes)
+		return 0;
+
 	if (size) {
 		if (offs > size)
 			return 0;
@@ -131,6 +134,9 @@ static ssize_t write(struct file *file, 
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 	char *temp;
 
+	if (!bytes)
+		return 0;
+
 	if (size) {
 		if (offs > size)
 			return 0;

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