Re: [PATCH] proc: fix null pointer deref in proc_pid_permission()

[Kees Cook]

Hi,

On Wed, Jan 11, 2012 at 01:47:05PM -0500, Xiaotian Feng wrote:
> get_proc_task() can fail to search the task and return NULL, put_task_struct()
> will then bomb the kernel with following oops:
> 
> [ 1870.574045] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> [ 1870.574065] IP: [<ffffffff81217d34>] proc_pid_permission+0x64/0xe0
> [ 1870.574088] PGD 112075067 PUD 112814067 PMD 0
> [ 1870.574106] Oops: 0002 [#1] PREEMPT SMP
> 
> This is a regression introduced by commit 0499680a, kernel should
> return -ESRCH if get_proc_task() failed.

Nice catch!

However since this error is returned to userspace, shouldn't this be
-ENOENT instead?

-Kees

-- 
Kees Cook
ChromeOS Security
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