6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kevin Groeneveld <kgroeneveld@xxxxxxxxxxxx>
[ Upstream commit 9499327714de7bc5cf6c792112c1474932d8ad31 ]
The configfs store callback should return the number of bytes consumed
not the total number of bytes we actually stored. These could differ if
for example the passed in string had a newline we did not store.
If the returned value does not match the number of bytes written the
writer might assume a failure or keep trying to write the remaining bytes.
For example the following command will hang trying to write the final
newline over and over again (tested on bash 2.05b):
echo foo > function_name
Fixes: 993a44fa85c1 ("usb: gadget: f_uac2: allow changing interface name via configfs")
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Kevin Groeneveld <kgroeneveld@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20241006232637.4267-1-kgroeneveld@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/usb/gadget/function/f_uac2.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 79d1f87c6cc59..b3dc5f5164f42 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -2052,7 +2052,7 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item, \
const char *page, size_t len) \
{ \
struct f_uac2_opts *opts = to_f_uac2_opts(item); \
- int ret = 0; \
+ int ret = len; \
\
mutex_lock(&opts->lock); \
if (opts->refcnt) { \
@@ -2063,8 +2063,8 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item, \
if (len && page[len - 1] == '\n') \
len--; \
\
- ret = scnprintf(opts->name, min(sizeof(opts->name), len + 1), \
- "%s", page); \
+ scnprintf(opts->name, min(sizeof(opts->name), len + 1), \
+ "%s", page); \
\
end: \
mutex_unlock(&opts->lock); \
--
2.43.0
