lkml.org 
[lkml]   [2012]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/5] ptrace: don't modify flags on PTRACE_SETOPTIONS failure
On 02/10, Denys Vlasenko wrote:

> On ptrace(PTRACE_SETOPTIONS, pid, 0, <opts>), we used to set
> those option bits which are known, and then fail with -EINVAL
> if there are some unknown bits in <opts>.
>
> This in inconsistent with typical error handling, which
> does not change any state if input is invalid.
>
> This patch changes PTRACE_SETOPTIONS behavior so that
> in this case, we return -EINVAL and don't change any bits
> in task->ptrace.
>
> It's very unlikely that there is userspace code in the wild which
> will be affected by this change: it should have the form
>
> ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_BOGUSOPT)
>
> where PTRACE_O_BOGUSOPT is a constant unknown to the kernel.
> But kernel headers, naturally, don't contain any
> PTRACE_O_BOGUSOPTs, thus the only way userspace can use one
> if it defines one itself. I can't see why anyone would do such
> a thing deliberately.
>
> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
> Acked-by: Tejun Heo <tj@kernel.org>

Reviewed-by: Oleg Nesterov <oleg@redhat.com>

> ---
> kernel/ptrace.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> index 00ab2ca..273f56e 100644
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -528,6 +528,9 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
>
> static int ptrace_setoptions(struct task_struct *child, unsigned long data)
> {
> + if (data & ~(unsigned long)PTRACE_O_MASK)
> + return -EINVAL;
> +
> child->ptrace &= ~PT_TRACE_MASK;
>
> if (data & PTRACE_O_TRACESYSGOOD)
> @@ -551,7 +554,7 @@ static int ptrace_setoptions(struct task_struct *child, unsigned long data)
> if (data & PTRACE_O_TRACEEXIT)
> child->ptrace |= PT_TRACE_EXIT;
>
> - return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
> + return 0;
> }
>
> static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
> --
> 1.7.7.6
>



\
 
 \ /
  Last update: 2012-02-10 18:25    [W:0.065 / U:18.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site