Patch "oprofile: Fix uninitialized memory access when writing to writing to oprofilefs" has been added to the 3.1-stable tree

[<gr...@su...>]

This is a note to let you know that I've just added the patch titled

    oprofile: Fix uninitialized memory access when writing to writing to oprofilefs

to the 3.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     oprofile-fix-uninitialized-memory-access-when-writing-to-writing-to-oprofilefs.patch
and it can be found in the queue-3.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <st...@vg...> know about it.


>From 913050b91eb94f194392dd797b1ff3779f606ac0 Mon Sep 17 00:00:00 2001
From: Robert Richter <rob...@am...>
Date: Mon, 19 Dec 2011 16:38:30 +0100
Subject: oprofile: Fix uninitialized memory access when writing to writing to oprofilefs

From: Robert Richter <rob...@am...>

commit 913050b91eb94f194392dd797b1ff3779f606ac0 upstream.

If oprofilefs_ulong_from_user() is called with count equals
zero, *val remains unchanged. Depending on the implementation it
might be uninitialized.

Change oprofilefs_ulong_from_user()'s interface to return count
on success. Thus, we are able to return early if count equals
zero which avoids using *val uninitialized. Fixing all users of
oprofilefs_ulong_ from_user().

This follows write syscall implementation when count is zero:
"If count is zero ... [and if] no errors are detected, 0 will be
returned without causing any other effect." (man 2 write)

Reported-By: Mike Waychison <mi...@go...>
Signed-off-by: Robert Richter <rob...@am...>
Cc: Andrew Morton <ak...@li...>
Cc: oprofile-list <opr...@li...>
Link: http://lkml.kernel.org/r/201...@er...
Signed-off-by: Ingo Molnar <mi...@el...>
Signed-off-by: Greg Kroah-Hartman <gr...@su...>

---
 arch/s390/oprofile/init.c         |    2 +-
 drivers/oprofile/oprofile_files.c |    7 ++++---
 drivers/oprofile/oprofilefs.c     |   11 +++++++++--
 3 files changed, 14 insertions(+), 6 deletions(-)

--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -88,7 +88,7 @@ static ssize_t hwsampler_write(struct fi
 		return -EINVAL;
 
 	retval = oprofilefs_ulong_from_user(&val, buf, count);
-	if (retval)
+	if (retval <= 0)
 		return retval;
 
 	if (oprofile_started)
--- a/drivers/oprofile/oprofile_files.c
+++ b/drivers/oprofile/oprofile_files.c
@@ -45,7 +45,7 @@ static ssize_t timeout_write(struct file
 		return -EINVAL;
 
 	retval = oprofilefs_ulong_from_user(&val, buf, count);
-	if (retval)
+	if (retval <= 0)
 		return retval;
 
 	retval = oprofile_set_timeout(val);
@@ -84,7 +84,7 @@ static ssize_t depth_write(struct file *
 		return -EINVAL;
 
 	retval = oprofilefs_ulong_from_user(&val, buf, count);
-	if (retval)
+	if (retval <= 0)
 		return retval;
 
 	retval = oprofile_set_ulong(&oprofile_backtrace_depth, val);
@@ -141,9 +141,10 @@ static ssize_t enable_write(struct file
 		return -EINVAL;
 
 	retval = oprofilefs_ulong_from_user(&val, buf, count);
-	if (retval)
+	if (retval <= 0)
 		return retval;
 
+	retval = 0;
 	if (val)
 		retval = oprofile_start();
 	else
--- a/drivers/oprofile/oprofilefs.c
+++ b/drivers/oprofile/oprofilefs.c
@@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigne
 }
 
 
+/*
+ * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
+ * unchanged and might be uninitialized. This follows write syscall
+ * implementation when count is zero: "If count is zero ... [and if]
+ * no errors are detected, 0 will be returned without causing any
+ * other effect." (man 2 write)
+ */
 int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
 {
 	char tmpbuf[TMPBUFSIZE];
@@ -79,7 +86,7 @@ int oprofilefs_ulong_from_user(unsigned
 	spin_lock_irqsave(&oprofilefs_lock, flags);
 	*val = simple_strtoul(tmpbuf, NULL, 0);
 	spin_unlock_irqrestore(&oprofilefs_lock, flags);
-	return 0;
+	return count;
 }
 
 
@@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct f
 		return -EINVAL;
 
 	retval = oprofilefs_ulong_from_user(&value, buf, count);
-	if (retval)
+	if (retval <= 0)
 		return retval;
 
 	retval = oprofile_set_ulong(file->private_data, value);


Patches currently in stable-queue which might be from rob...@am... are

queue-3.1/oprofile-fix-uninitialized-memory-access-when-writing-to-writing-to-oprofilefs.patch