Patch "kernfs: fix regression in kernfs_fop_write caused by wrong type" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

kernfs: fix regression in kernfs_fop_write caused by wrong type

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kernfs-fix-regression-in-kernfs_fop_write-caused-by-wrong-type.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ivan Vecera <[email protected]>
Date: Fri, 19 Jan 2018 09:18:54 +0100
Subject: kernfs: fix regression in kernfs_fop_write caused by wrong type

From: Ivan Vecera <[email protected]>

commit ba87977a49913129962af8ac35b0e13e0fa4382d upstream.

Commit b7ce40cff0b9 ("kernfs: cache atomic_write_len in kernfs_open_file") changes type of local variable 'len' from ssize_t to size_t. This change caused that the *ppos value is updated also when the previous write callback failed.

Mentioned snippet:
...
len = ops->write(...); <- return value can be negative
...
if (len > 0) <- true here in this case

        *ppos += len;

...

---
 fs/kernfs/file.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -275,7 +275,7 @@ static ssize_t kernfs_fop_write(struct f
 {
 	struct kernfs_open_file *of = kernfs_of(file);
 	const struct kernfs_ops *ops;
-	size_t len;
+	ssize_t len;
 	char *buf;
 
 	if (of->atomic_write_len) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/kernfs-fix-regression-in-kernfs_fop_write-caused-by-wrong-type.patch