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Subject[PATCH] oprofilefs: Handle zero-length writes.
Date
Currently in oprofilefs, files that use ulong_fops mis-handle writes of
zero length. A count of 0 causes oprofilefs_ulong_from_user to return
0 (success), which then leads to oprofile_set_ulong being called to
stuff "value" into file->private_data without it being initialized.

Fix this by moving the check for a zero-length write up into
ulong_write_file.

Signed-off-by: Mike Waychison <mikew@google.com>
---
drivers/oprofile/oprofilefs.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c
index e9ff6f7..ee14e6e 100644
--- a/drivers/oprofile/oprofilefs.c
+++ b/drivers/oprofile/oprofilefs.c
@@ -65,9 +65,6 @@ int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_
char tmpbuf[TMPBUFSIZE];
unsigned long flags;

- if (!count)
- return 0;
-
if (count > TMPBUFSIZE - 1)
return -EINVAL;

@@ -97,6 +94,8 @@ static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_

if (*offset)
return -EINVAL;
+ if (count == 0)
+ return 0;

retval = oprofilefs_ulong_from_user(&value, buf, count);
if (retval)
--
1.7.3.1


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