Messages in this thread Patch in this message | | | From | Denys Vlasenko <> | Subject | [PATCH 1/2] ptrace: don't modify flags on PTRACE_SETOPTIONS failure | Date | Fri, 9 Sep 2011 08:24:37 +0200 |
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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 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 <dvlasenk@redhat.com> ---
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 9de3ecf..02df3c1 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -509,6 +509,9 @@ 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) @@ -532,7 +535,7 @@ 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)
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