Messages in this thread | | | Date | Mon, 2 Oct 2023 15:12:35 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86_64: test that userspace stack is in fact NX |
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* Alexey Dobriyan <adobriyan@gmail.com> wrote:
> Here is how it works: > > * fault and fill the stack from rsp with int3 down until rlimit allows, > * fill upwards with int3 too, overwrite libc stuff, argv, envp, > * try to exec int3 on each page and catch it with either SIGSEGV or > SIGTRAP handler. > > Note: trying to execute _every_ int3 takes 30-40 seconds even on fast > machine, so only 1 int3 per page is tried. > > Tested on F37 kernel and on custom kernel which did > > vm_flags |= VM_EXEC; > > to stack VMA. > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > --- > > tools/testing/selftests/x86/Makefile | 3 > tools/testing/selftests/x86/nx_stack.c | 167 +++++++++++++++++++++++++++++++++ > 2 files changed, 170 insertions(+)
Ok, that's a good idea, but could the test case please output something human-readable that indicates whether the test was a success or not?
A typical testcase output is like:
kepler:~/tip/tools/testing/selftests/x86> ./sigaltstack_32 [RUN] Test an alternate signal stack of sufficient size. Raise SIGALRM. It is expected to be delivered. [OK] SIGALRM signal delivered.
Or:
kepler:~/tip/tools/testing/selftests/x86> ./test_vsyscall_64 ... [OK] vsyscalls are emulated (1 instructions in vsyscall page) ...
... where the 'OK' denotes success of a test.
The nx_stack testcase only outputs:
stack min 00007fffd75b5000 stack max 00007fffd7db5000
... with only the exit code denoting success/failure.
Thanks,
Ingo
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