4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ivan Vecera <ivecera@xxxxxxxxxx>
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;
...
Fixes: b7ce40cff0b9 ("kernfs: cache atomic_write_len in kernfs_open_file")
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Ivan Vecera <ivecera@xxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/kernfs/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -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) {