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SubjectRe: [PATCH] proc/pid/cmdline: Handle invalid cmdline change failures correctly.
On Sat, 03 Oct 2009 00:07:12 -0400
Timo Sirainen <tss@iki.fi> wrote:

> Handle access_process_vm() failures correctly in /proc/pid/cmdline.
> This bug might have leaked kernel memory to userspace.
>

The changelog fails to describe the bug.

> ---
> fs/proc/base.c | 7 ++++---
> 1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 837469a..f66cc4c 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -252,7 +252,7 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
>
> static int proc_pid_cmdline(struct task_struct *task, char * buffer)
> {
> - int res = 0;
> + int res = 0, res2;
> unsigned int len;
> struct mm_struct *mm = get_task_mm(task);
> if (!mm)
> @@ -277,8 +277,9 @@ static int proc_pid_cmdline(struct task_struct *task, char * buffer)
> len = mm->env_end - mm->env_start;
> if (len > PAGE_SIZE - res)
> len = PAGE_SIZE - res;
> - res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
> - res = strnlen(buffer, res);
> + res2 = access_process_vm(task, mm->env_start, buffer+res, len, 0);
> + if (res2 > 0)
> + res = strnlen(buffer, res + res2);
> }
> }

And I don't see what it is. afacit the current code is correct.


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