linux-kernel - [patch v2] usb: f_fs: off by one bug in _ffs_func

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Message-ID: <20160528044810.GA4107@mwanda>
Date:	Sat, 28 May 2016 07:48:10 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Felipe Balbi <balbi@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Michal Nazarewicz <mina86@...a86.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Robert Baldyga <r.baldyga@...sung.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	Daniel Walter <dwalter@...ma-star.at>,
	"Du, Changbin" <changbin.du@...el.com>,
	Rui Miguel Silva <rui.silva@...aro.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch v2] usb: f_fs: off by one bug in _ffs_func_bind()

This loop is supposed to set all the .num[] values to -1 but it's off by
one so it skips the first element and sets one element past the end of
the array.

I've cleaned up the loop a little as well.

Fixes: ddf8abd25994 ('USB: f_fs: the FunctionFS driver')
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
v2: move the eps_ptr assignment outside the loop.

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 73515d5..d26eb64 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -2729,6 +2729,7 @@ static int _ffs_func_bind(struct usb_configuration *c,
 		func->ffs->ss_descs_count;
 
 	int fs_len, hs_len, ss_len, ret, i;
+	struct ffs_ep *eps_ptr;
 
 	/* Make it a single chunk, less management later on */
 	vla_group(d);
@@ -2777,12 +2778,9 @@ static int _ffs_func_bind(struct usb_configuration *c,
 	       ffs->raw_descs_length);
 
 	memset(vla_ptr(vlabuf, d, inums), 0xff, d_inums__sz);
-	for (ret = ffs->eps_count; ret; --ret) {
-		struct ffs_ep *ptr;
-
-		ptr = vla_ptr(vlabuf, d, eps);
-		ptr[ret].num = -1;
-	}
+	eps_ptr = vla_ptr(vlabuf, d, eps);
+	for (i = 0; i < ffs->eps_count; i++)
+		eps_ptr[i].num = -1;
 
 	/* Save pointers
 	 * d_eps == vlabuf, func->eps used to kfree vlabuf later