Commit 8c5cf9e5 authored Mar 23, 2012 by Denys Vlasenko Committed by Linus Torvalds Mar 23, 2012

ptrace: don't modify flags on PTRACE_SETOPTIONS failure



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 is 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>
Cc: Pedro Alves <palves@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent b1845ff5

kernel/ptrace.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -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)