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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dean Anderson <dean@sensoray.com>
Subject: [PATCH 4.19 109/425] usb: gadget/function/f_fs string table fix for multiple languages
Date:   Thu, 20 May 2021 11:17:58 +0200
Message-Id: <20210520092135.034026932@linuxfoundation.org>
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References: <20210520092131.308959589@linuxfoundation.org>
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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
@@ -2553,6 +2553,7 @@ 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;
@@ -2588,7 +2589,7 @@ 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;