From: Ivan Vecera <ivecera@xxxxxxxxxx>
This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit ba87977a49913129962af8ac35b0e13e0fa4382d ]
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: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
fs/kernfs/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 9ff28bc294c0..5d084638e1f8 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -272,7 +272,7 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
{
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) {
--
2.14.1