On Fri, Jul 25, 2014 at 11:36:49AM +0100, AKASHI Takahiro wrote:

On 07/25/2014 12:01 AM, Andy Lutomirski wrote:

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If so, then you risk (at least) introducing

a nice user-triggerable OOPS if audit is enabled.

Can you please elaborate this?
Since I didn't find any definition of audit's behavior when syscall is
rewritten to -1, I thought it is reasonable to skip "exit tracing" of
"skipped" syscall.
(otherwise, "fake" seems to be more appropriate :)

The audit entry hook will oops if you call it twice in a row without
calling the exit hook in between.

Thank you, I could reproduce this problem which hits BUG(in_syscall) in
audit_syscall_entry(). Really bad, and I fixed it in my next version and
now a "skipped" system call is also traced by audit.

Can you reproduce this on arch/arm/ too? If so, we should also fix the code
there.

Will