On Fri, Apr 22, 2011 at 03:16:27PM +0200, Frederic Weisbecker wrote:
> (resend with ppc list in cc)
>
> While the tracer accesses ptrace breakpoints, the child task may
> concurrently exit due to a SIGKILL and thus release its breakpoints
> at the same time. We can then dereference some freed pointers.
>
> To fix this, hold a reference on the child breakpoints before
> manipulating them.
>
> Reported-by: Oleg Nesterov <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Benjamin Herrenschmidt <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Prasad <[email protected]>
> Cc: Paul Mundt <[email protected]>
> Cc: v2.6.33.. <[email protected]>
> ---
> arch/powerpc/kernel/ptrace.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> index 55613e3..4edeeb3 100644
> --- a/arch/powerpc/kernel/ptrace.c
> +++ b/arch/powerpc/kernel/ptrace.c
> @@ -1591,7 +1591,10 @@ long arch_ptrace(struct task_struct *child, long
> request,
> }
>
> case PTRACE_SET_DEBUGREG:
> + if (ptrace_get_breakpoints(child) < 0)
> + return -ESRCH;
> ret = ptrace_set_debugreg(child, addr, data);
> + ptrace_put_breakpoints(child);
> break;
>
> #ifdef CONFIG_PPC64
> --
> 1.7.3.2
>
Hi Frederic,
Looks fine to me.
Acked-by: K.Prasad <[email protected]>
Thanks,
K.Prasad
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