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Commit 913050b9 authored by Robert Richter's avatar Robert Richter Committed by Ingo Molnar
Browse files

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



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: default avatarMike Waychison <mikew@google.com>
Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Cc: oprofile-list <oprofile-list@lists.sourceforge.net>
Link: http://lkml.kernel.org/r/20111219153830.GH16765@erda.amd.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 497f16f2

arch/s390/oprofile/init.c

+1 −1
Original line number Diff line number Diff line
@@ -88,7 +88,7 @@ static ssize_t hwsampler_write(struct file *file, char const __user *buf, 
		return -EINVAL;



	retval = oprofilefs_ulong_from_user(&val, buf, count);

	if (retval)

	if (retval <= 0)

		return retval;



	if (oprofile_started)

drivers/oprofile/oprofile_files.c

+4 −3
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ static ssize_t timeout_write(struct file *file, char const __user *buf, 
		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 *file, char const __user *buf, size_t cou 
		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 *file, char const __user *buf, size_t co 
		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

drivers/oprofile/oprofilefs.c

+9 −2
Original line number Diff line number Diff line
@@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t cou 
}





/*

 * 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 long *val, char const __user *buf, size_ 
	raw_spin_lock_irqsave(&oprofilefs_lock, flags);

	*val = simple_strtoul(tmpbuf, NULL, 0);

	raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);

	return 0;

	return count;

}
@@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_ 
		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);