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Re: How to change a string type argument of a system call?

From: fche at redhat dot com (Frank Ch. Eigler)
To: Josh Stone <jistone at redhat dot com>
Cc: Neo Liu <diabloneo at gmail dot com>, SystemTap <systemtap at sourceware dot org>
Date: Mon, 05 Apr 2010 23:59:07 -0400
Subject: Re: How to change a string type argument of a system call?
References: <o2k861674c01004010514k8e3d095ew7e11232f6fdf3dbb@mail.gmail.com> <y0md3yjgv7y.fsf@fche.csb> <t2p861674c01004031854i13e04e4ay551536bce99c0785@mail.gmail.com> <g2h861674c01004031856tabb21c2anbc5e9dfb2836acc2@mail.gmail.com> <4BBA01A5.1060503@redhat.com>

Josh Stone <jistone@redhat.com> writes:

> [...]
> Correct -- the open syscall gets the filename using strncpy_from_user,
> which verifies that the pointer is within the user's address space.
> 
> I can think of a few options for you:
> [...]

5) use set_fs(KERN_DS) in some entry-probe-time embedded-c, with
   a corresponding set_fs(USER_DS) or whatnot at return-probe-time.

- FChE

Follow-Ups:
- Re: How to change a string type argument of a system call?
  - From: Neo Liu

References:
- How to change a string type argument of a system call?
  - From: Neo Liu
- Re: How to change a string type argument of a system call?
  - From: Frank Ch. Eigler
- Re: How to change a string type argument of a system call?
  - From: Neo Liu
- Re: How to change a string type argument of a system call?
  - From: Josh Stone

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