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Re: lib/test_overflow.c causes WARNING and tainted kernel




Hi!

On Wed, Mar 13, 2019 at 2:29 PM Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote:
>
> This is v5.0-11053-gebc551f2b8f9, MAR-12 around 4:00pm PT.
>
> In the first test_kmalloc() in test_overflow_allocation():
>
> [54375.073895] test_overflow: ok: (s64)(0 << 63) == 0
> [54375.074228] WARNING: CPU: 2 PID: 5462 at ../mm/page_alloc.c:4584 __alloc_pages_nodemask+0x33f/0x540
> [...]
> [54375.079236] ---[ end trace 754acb68d8d1a1cb ]---
> [54375.079313] test_overflow: kmalloc detected saturation

Yup! This is expected and operating as intended: it is exercising the
allocator's detection of insane allocation sizes. :)

If we want to make it less noisy, perhaps we could add a global flag
the allocators could check before doing their WARNs?

-Kees

-- 
Kees Cook