[3.13.y-ckt stable] Patch "mwifiex: fix mwifiex_rdeeprom_read()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    mwifiex: fix mwifiex_rdeeprom_read()

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt31.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From aa81da86cd1c7f66cdc67f4be7fd88bc19bf23d6 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter at oracle.com>
Date: Mon, 21 Sep 2015 19:19:53 +0300
Subject: mwifiex: fix mwifiex_rdeeprom_read()

commit 1f9c6e1bc1ba5f8a10fcd6e99d170954d7c6d382 upstream.

There were several bugs here.

1)  The done label was in the wrong place so we didn't copy any
    information out when there was no command given.

2)  We were using PAGE_SIZE as the size of the buffer instead of
    "PAGE_SIZE - pos".

3)  snprintf() returns the number of characters that would have been
    printed if there were enough space.  If there was not enough space
    (and we had fixed the memory corruption bug #2) then it would result
    in an information leak when we do simple_read_from_buffer().  I've
    changed it to use scnprintf() instead.

I also removed the initialization at the start of the function, because
I thought it made the code a little more clear.

Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell mwifiex driver')
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Acked-by: Amitkumar Karwar <akarwar at marvell.com>
Signed-off-by: Kalle Valo <kvalo at codeaurora.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/wireless/mwifiex/debugfs.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/mwifiex/debugfs.c b/drivers/net/wireless/mwifiex/debugfs.c
index a5f9875..f84e5d7e 100644
--- a/drivers/net/wireless/mwifiex/debugfs.c
+++ b/drivers/net/wireless/mwifiex/debugfs.c
@@ -637,7 +637,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
 		(struct mwifiex_private *) file->private_data;
 	unsigned long addr = get_zeroed_page(GFP_KERNEL);
 	char *buf = (char *) addr;
-	int pos = 0, ret = 0, i;
+	int pos, ret, i;
 	u8 value[MAX_EEPROM_DATA];

 	if (!buf)
@@ -645,7 +645,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,

 	if (saved_offset == -1) {
 		/* No command has been given */
-		pos += snprintf(buf, PAGE_SIZE, "0");
+		pos = snprintf(buf, PAGE_SIZE, "0");
 		goto done;
 	}

@@ -654,17 +654,17 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
 				  (u16) saved_bytes, value);
 	if (ret) {
 		ret = -EINVAL;
-		goto done;
+		goto out_free;
 	}

-	pos += snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset, saved_bytes);
+	pos = snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset, saved_bytes);

 	for (i = 0; i < saved_bytes; i++)
-		pos += snprintf(buf + strlen(buf), PAGE_SIZE, "%d ", value[i]);
-
-	ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
+		pos += scnprintf(buf + pos, PAGE_SIZE - pos, "%d ", value[i]);

 done:
+	ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
+out_free:
 	free_page(addr);
 	return ret;
 }
--
1.9.1