[PATCH 4.9 064/240] usb: gadget/function/f_fs string table fix for multiple languages

Greg Kroah-Hartman
2021-05-20T11:09:05Z

From: Dean Anderson <dean@sensoray.com>

commit 55b74ce7d2ce0b0058f3e08cab185a0afacfe39e upstream.

Fixes bug with the handling of more than one language in
the string table in f_fs.c.
str_count was not reset for subsequent language codes.
str_count-- "rolls under" and processes u32 max strings on
the processing of the second language entry.
The existing bug can be reproduced by adding a second language table
to the structure "strings" in tools/usb/ffs-test.c.

Signed-off-by: Dean Anderson <dean@sensoray.com>
Link: https://lore.kernel.org/r/20210317224109.21534-1-dean@sensoray.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/gadget/function/f_fs.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -2543,6 +2543,7 @@ static int __ffs_data_got_strings(struct

do { /* lang_count > 0 so we can use do-while */
unsigned needed = needed_count;
+ u32 str_per_lang = str_count;

if (unlikely(len < 3))
goto error_free;
@@ -2578,7 +2579,7 @@ static int __ffs_data_got_strings(struct

data += length + 1;
len -= length + 1;
- } while (--str_count);
+ } while (--str_per_lang);

s->id = 0; /* terminator */
s->s = NULL;