Messages in this thread |  | | Date | Fri, 10 Feb 2012 18:17:03 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/5] ptrace: don't modify flags on PTRACE_SETOPTIONS failure |
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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 >
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