From: Thomas Gleixner <tglx@linutronix.de>
To: Alexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <andreyknvl@google.com>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>, Christoph Hellwig <hch@lst.de>,
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Dmitry Vyukov <dvyukov@google.com>,
Eric Dumazet <edumazet@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Ilya Leoshkevich <iii@linux.ibm.com>,
Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
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Matthew Wilcox <willy@infradead.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
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Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Vasily Gorbik <gor@linux.ibm.com>,
Vegard Nossum <vegard.nossum@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux Memory Management List <linux-mm@kvack.org>,
Linux-Arch <linux-arch@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 28/46] kmsan: entry: handle register passing from uninstrumented code
Date: Fri, 06 May 2022 20:41:01 +0200 [thread overview]
Message-ID: <87h762h5c2.ffs@tglx> (raw)
In-Reply-To: <CAG_fn=UpcXMqJiZvho6_G3rjvjQA-3Ax6X8ONVO0D+4Pttc9dA@mail.gmail.com>
On Fri, May 06 2022 at 19:41, Alexander Potapenko wrote:
> On Fri, May 6, 2022 at 6:14 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>> sysvec_apic_timer_interrupt() invokes irqentry_enter() _before_
>> set_irq_regs() and irqentry_enter() unpoisons @reg.
>>
>> Confused...
>
> As far as I can tell in this case sysvect_apic_timer_interrupt() is
> called by the following code in arch/x86/kernel/idt.c:
>
> INTG(LOCAL_TIMER_VECTOR, asm_sysvec_apic_timer_interrupt),
>
> , which does not use IDTENTRY_SYSVEC framework and thus does not call
> irqentry_enter().
asm_sysvec_apic_timer_interrupt != sysvec_apic_timer_interrupt
arch/x86/kernel/apic/apic.c:
DEFINE_IDTENTRY_SYSVEC(sysvec_apic_timer_interrupt)
{
....
#define DEFINE_IDTENTRY_SYSVEC(func) \
static void __##func(struct pt_regs *regs); \
\
__visible noinstr void func(struct pt_regs *regs) \
{ \
irqentry_state_t state = irqentry_enter(regs); \
....
__##func (regs); \
....
} \
\
static noinline void __##func(struct pt_regs *regs)
So it goes through that code path _before_ the actual implementation
which does set_irq_regs() is reached.
The callchain is:
asm_sysvec_apic_timer_interrupt <- ASM entry in gate
sysvec_apic_timer_interrupt(regs) <- noinstr C entry point
irqentry_enter(regs) <- unpoisons @reg
__sysvec_apic_timer_interrupt(regs) <- the actual handler
set_irq_regs(regs) <- stores regs
local_apic_timer_interrupt()
...
tick_handler() <- One of the 4 variants
regs = get_irq_regs(); <- retrieves regs
update_process_times(user_tick = user_mode(regs))
account_process_tick(user_tick)
irqtime_account_process_tick(user_tick)
line 382: } else if { user_tick } <- KMSAN complains
I'm even more confused now.
> I guess handling those will require wrapping every interrupt gate into
> a function that performs register unpoisoning?
No, guessing does not help here.
The gates point to the ASM entry point, which then invokes the C entry
point. All C entry points use a DEFINE_IDTENTRY variant.
Some of the DEFINE_IDTENTRY_* C entry points are not doing anything in
the macro, but the C function either invokes irqentry_enter() or
irqentry_nmi_enter() open coded _before_ invoking any instrumentable
function. So the unpoisoning of @regs in these functions should tell
KMSAN that @regs or something derived from @regs are not some random
uninitialized values.
There should be no difference between unpoisoning @regs in
irqentry_enter() or in set_irq_regs(), right?
If so, then the problem is definitely _not_ the idt entry code.
> By the way, if it helps, I think we don't necessarily have to call
> kmsan_unpoison_memory() from within the
> instrumentation_begin()/instrumentation_end() region?
> We could move the call to the beginning of irqentry_enter(), removing
> unnecessary duplication.
We could, but then you need to mark unpoison_memory() noinstr too and you
have to add the unpoison into the syscall code. No win and irrelevant to
the problem at hand.
Thanks,
tglx
next prev parent reply other threads:[~2022-05-06 18:41 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 16:42 [PATCH v3 00/46] Add KernelMemorySanitizer infrastructure Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 01/46] x86: add missing include to sparsemem.h Alexander Potapenko
2022-04-27 13:22 ` Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 02/46] stackdepot: reserve 5 extra bits in depot_stack_handle_t Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 03/46] kasan: common: adapt to the new prototype of __stack_depot_save() Alexander Potapenko
2022-04-27 12:47 ` Marco Elver
2022-04-26 16:42 ` [PATCH v3 04/46] instrumented.h: allow instrumenting both sides of copy_from_user() Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 05/46] x86: asm: instrument usercopy in get_user() and __put_user_size() Alexander Potapenko
2022-04-27 3:45 ` kernel test robot
2022-04-27 6:58 ` kernel test robot
2022-04-27 7:14 ` Arnd Bergmann
2022-06-02 11:20 ` Alexander Potapenko
2022-04-27 14:24 ` kernel test robot
2022-04-28 1:59 ` kernel test robot
2022-04-30 10:16 ` [x86] d216de19c8: kernel-selftests.x86.ioperm_32.fail kernel test robot
2022-04-26 16:42 ` [PATCH v3 06/46] asm-generic: instrument usercopy in cacheflush.h Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 07/46] kmsan: add ReST documentation Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 08/46] kmsan: introduce __no_sanitize_memory and __no_kmsan_checks Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 09/46] kmsan: mark noinstr as __no_sanitize_memory Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 10/46] x86: kmsan: pgtable: reduce vmalloc space Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 11/46] libnvdimm/pfn_dev: increase MAX_STRUCT_PAGE_SIZE Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 12/46] kmsan: add KMSAN runtime core Alexander Potapenko
2022-04-27 14:09 ` Marco Elver
2022-05-31 11:08 ` Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 13/46] kmsan: implement kmsan_init(), initialize READ_ONCE_NOCHECK() Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 14/46] kmsan: disable instrumentation of unsupported common kernel code Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 15/46] MAINTAINERS: add entry for KMSAN Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 16/46] kmsan: mm: maintain KMSAN metadata for page operations Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 17/46] kmsan: mm: call KMSAN hooks from SLUB code Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 18/46] kmsan: handle task creation and exiting Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 19/46] kmsan: init: call KMSAN initialization routines Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 20/46] instrumented.h: add KMSAN support Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 21/46] kmsan: unpoison @tlb in arch_tlb_gather_mmu() Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 22/46] kmsan: add iomap support Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 23/46] Input: libps2: mark data received in __ps2_command() as initialized Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 24/46] kmsan: dma: unpoison DMA mappings Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 25/46] kmsan: virtio: check/unpoison scatterlist in vring_map_one_sg() Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 26/46] kmsan: handle memory sent to/from USB Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 27/46] kmsan: instrumentation.h: add instrumentation_begin_with_regs() Alexander Potapenko
2022-04-27 13:28 ` Thomas Gleixner
2022-05-16 11:49 ` Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 28/46] kmsan: entry: handle register passing from uninstrumented code Alexander Potapenko
2022-04-27 13:32 ` Thomas Gleixner
2022-05-02 17:00 ` Alexander Potapenko
2022-05-02 22:00 ` Thomas Gleixner
2022-05-05 18:04 ` Alexander Potapenko
2022-05-05 21:56 ` Thomas Gleixner
2022-05-06 14:52 ` Alexander Potapenko
2022-05-06 16:14 ` Thomas Gleixner
2022-05-06 17:41 ` Alexander Potapenko
2022-05-06 18:41 ` Thomas Gleixner [this message]
2022-05-09 16:50 ` Alexander Potapenko
2022-05-09 16:51 ` Alexander Potapenko
2022-05-09 19:09 ` Thomas Gleixner
2022-05-12 12:24 ` Alexander Potapenko
2022-05-12 16:17 ` Thomas Gleixner
2022-05-12 16:48 ` Thomas Gleixner
2022-06-01 11:27 ` Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 29/46] kmsan: add tests for KMSAN Alexander Potapenko
2022-04-26 16:42 ` [PATCH v3 30/46] kmsan: disable strscpy() optimization under KMSAN Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 31/46] crypto: kmsan: disable accelerated configs " Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 32/46] kmsan: disable physical page merging in biovec Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 33/46] kmsan: block: skip bio block merging logic for KMSAN Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 34/46] kmsan: kcov: unpoison area->list in kcov_remote_area_put() Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 35/46] security: kmsan: fix interoperability with auto-initialization Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 36/46] objtool: kmsan: list KMSAN API functions as uaccess-safe Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 37/46] x86: kmsan: make READ_ONCE_TASK_STACK() return initialized values Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 38/46] x86: kmsan: disable instrumentation of unsupported code Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 39/46] x86: kmsan: skip shadow checks in __switch_to() Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 40/46] x86: kmsan: handle open-coded assembly in lib/iomem.c Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 41/46] x86: kmsan: use __msan_ string functions where possible Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 42/46] x86: kmsan: sync metadata pages on page fault Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 43/46] x86: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 44/46] x86: fs: kmsan: disable CONFIG_DCACHE_WORD_ACCESS Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 45/46] x86: kmsan: handle register passing from uninstrumented code Alexander Potapenko
2022-04-26 16:43 ` [PATCH v3 46/46] x86: kmsan: enable KMSAN builds for x86 Alexander Potapenko
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