[ 3.5.y.z extended stable ] Patch "regmap: debugfs: Avoid overflows for very small reads" has been added to staging queue

[Herton Ronaldo Krzesinski]

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

    regmap: debugfs: Avoid overflows for very small reads

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

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

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 983c0d5b12ff4101be0efb24be5b67e1affeaac5 Mon Sep 17 00:00:00 2001
From: Mark Brown <broonie at opensource.wolfsonmicro.com>
Date: Tue, 11 Dec 2012 01:14:11 +0900
Subject: [PATCH] regmap: debugfs: Avoid overflows for very small reads

commit db04328c167ff8e7c57f4a3532214aeada3a82fd upstream.

If count is less than the size of a register then we may hit integer
wraparound when trying to move backwards to check if we're still in
the buffer. Instead move the position forwards to check if it's still
in the buffer, we are unlikely to be able to allocate a buffer
sufficiently big to overflow here.

Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
[ herton: on 3.5, code is in regmap_map_read_file, and size in tot_len ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/base/regmap/regmap-debugfs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index bb1ff17..c394041 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -90,7 +90,7 @@ static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
 		/* If we're in the region the user is trying to read */
 		if (p >= *ppos) {
 			/* ...but not beyond it */
-			if (buf_pos >= count - 1 - tot_len)
+			if (buf_pos + 1 + tot_len >= count)
 				break;

 			/* Format the register */
--
1.7.9.5