[56/70] proc: do proper range check on readdir offset

From: Greg KH
Date: Tue Apr 19 2011 - 16:17:48 EST


2.6.38-stable review patch. If anyone has any objections, please let us know.

------------------

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

commit d8bdc59f215e62098bc5b4256fd9928bf27053a1 upstream.

Rather than pass in some random truncated offset to the pid-related
functions, check that the offset is in range up-front.

This is just cleanup, the previous commit fixed the real problem.

Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
fs/proc/base.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3066,11 +3066,16 @@ static int proc_pid_fill_cache(struct fi
/* for the /proc/ directory itself, after non-process stuff has been done */
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
- unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
- struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
+ unsigned int nr;
+ struct task_struct *reaper;
struct tgid_iter iter;
struct pid_namespace *ns;

+ if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
+ goto out_no_task;
+ nr = filp->f_pos - FIRST_PROCESS_ENTRY;
+
+ reaper = get_proc_task(filp->f_path.dentry->d_inode);
if (!reaper)
goto out_no_task;



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