[PATCH 5.19 0964/1157] kfifo: fix kfifo_to_user() return type

Greg Kroah-Hartman
2022-08-16T00:53:30Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 045ed31e23aea840648c290dbde04797064960db ]

The kfifo_to_user() macro is supposed to return zero for success or
negative error codes. Unfortunately, there is a signedness bug so it
returns unsigned int. This only affects callers which try to save the
result in ssize_t and as far as I can see the only place which does that
is line6_hwdep_read().

TL;DR: s/_uint/_int/.

Link: https://lkml.kernel.org/r/YrVL3OJVLlNhIMFs@kili
Fixes: 144ecf310eb5 ("kfifo: fix kfifo_alloc() to return a signed int value")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/kfifo.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
index 86249476b57f..0b35a41440ff 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -688,7 +688,7 @@ __kfifo_uint_must_check_helper( \
* writer, you don't need extra locking to use these macro.
*/
#define kfifo_to_user(fifo, to, len, copied) \
-__kfifo_uint_must_check_helper( \
+__kfifo_int_must_check_helper( \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
void __user *__to = (to); \
--
2.35.1