On Thu, 30 Oct 2014 07:10:39 -0400
Steven Rostedt [off-list ref] wrote:

On Thu, 30 Oct 2014 10:18:08 +0000
Russell King - ARM Linux [off-list ref] wrote:

quoted

On Thu, Oct 30, 2014 at 01:26:06AM -0700, Christoph Hellwig wrote:

quoted

On Wed, Oct 29, 2014 at 11:06:58PM +0100, Rabin Vincent wrote:

quoted

ARM has some private syscalls (for example, set_tls(2)) which lie
outside the range of NR_syscalls.  If any of these are called while
syscall tracing is being performed, out-of-bounds array access will
occur in the ftrace and perf sys_{enter,exit} handlers.

While this patch looks like good caution, having syscalls outside of
NR_syscalls seems like a receipe for a disaster.  Can you try to fix
that issue as ell, please?

No.  We've had them since the inception of Linux on ARM.  They predate
this tracing crap by more than a decade.  We're not changing them
because that would be a massive user API breakage.

Since syscall tracing is only broken on ARM, then the fix needs to be
ARM specific, and not remove the check for all other architectures that
have a sane NR_syscalls variable.

Bah, I misread the patch. I shouldn't read patches before having my
morning coffee :-/

I read it backwards. I thought it was removing the checks for
NR_syscalls, and not adding them.

I'm fine with the patch as is, and will take it.

But I agree that the syscall tracing code needs a rewrite to handle
these types of issues. It has problems with compat calls as well, which
we simply ignore.

Sorry for the confusion.

-- Steve