linux-kernel - [PATCH -fixes v2 0/4] Fixes KASAN and other along the way

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Message-Id: <20220221161232.2168364-1-alexandre.ghiti@canonical.com>
Date:   Mon, 21 Feb 2022 17:12:28 +0100
From:   Alexandre Ghiti <alexandre.ghiti@...onical.com>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexandre Ghiti <alexandre.ghiti@...onical.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Nick Hu <nickhu@...estech.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com
Subject: [PATCH -fixes v2 0/4] Fixes KASAN and other along the way

As reported by Aleksandr, syzbot riscv is broken since commit
54c5639d8f50 ("riscv: Fix asan-stack clang build"). This commit actually
breaks KASAN_INLINE which is not fixed in this series, that will come later
when found.

Nevertheless, this series fixes small things that made the syzbot
configuration + KASAN_OUTLINE fail to boot.

Note that even though the config at [1] boots fine with this series, I
was not able to boot the small config at [2] which fails because
kasan_poison receives a really weird address 0x4075706301000000 (maybe a
kasan person could provide some hint about what happens below in
do_ctors -> __asan_register_globals):

Thread 2 hit Breakpoint 1, kasan_poison (addr=<optimized out>, size=<optimized out>, value=<optimized out>, init=<optimized out>) at /home/alex/work/linux/mm/kasan/shadow.c:90
90		if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
1: x/i $pc
=> 0xffffffff80261712 <kasan_poison>:	andi	a4,a0,7
5: /x $a0 = 0x4075706301000000

Thread 2 hit Breakpoint 2, handle_exception () at /home/alex/work/linux/arch/riscv/kernel/entry.S:27
27		csrrw tp, CSR_SCRATCH, tp
1: x/i $pc
=> 0xffffffff80004098 <handle_exception>:	csrrw	tp,sscratch,tp
5: /x $a0 = 0xe80eae0b60200000
(gdb) bt
#0  handle_exception () at /home/alex/work/linux/arch/riscv/kernel/entry.S:27
#1  0xffffffff80261746 in kasan_poison (addr=<optimized out>, size=<optimized out>, value=<optimized out>, init=<optimized out>)
    at /home/alex/work/linux/mm/kasan/shadow.c:98
#2  0xffffffff802618b4 in kasan_unpoison (addr=<optimized out>, size=<optimized out>, init=<optimized out>)
    at /home/alex/work/linux/mm/kasan/shadow.c:138
#3  0xffffffff80260876 in register_global (global=<optimized out>) at /home/alex/work/linux/mm/kasan/generic.c:214
#4  __asan_register_globals (globals=<optimized out>, size=<optimized out>) at /home/alex/work/linux/mm/kasan/generic.c:226
#5  0xffffffff8125efac in _sub_I_65535_1 ()
#6  0xffffffff81201b32 in do_ctors () at /home/alex/work/linux/init/main.c:1156
#7  do_basic_setup () at /home/alex/work/linux/init/main.c:1407
#8  kernel_init_freeable () at /home/alex/work/linux/init/main.c:1613
#9  0xffffffff81153ddc in kernel_init (unused=<optimized out>) at /home/alex/work/linux/init/main.c:1502
#10 0xffffffff800041c0 in handle_exception () at /home/alex/work/linux/arch/riscv/kernel/entry.S:231


Thanks again to Aleksandr for narrowing down the issues fixed here.


[1] https://gist.github.com/a-nogikh/279c85c2d24f47efcc3e865c08844138
[2] https://gist.github.com/AlexGhiti/a5a0cab0227e2bf38f9d12232591c0e4


Changes in v2:
- Fix kernel test robot failure regarding KERN_VIRT_SIZE that is
  undefined for nommu config

Alexandre Ghiti (4):
  riscv: Fix is_linear_mapping with recent move of KASAN region
  riscv: Fix config KASAN && SPARSEMEM && !SPARSE_VMEMMAP
  riscv: Fix DEBUG_VIRTUAL false warnings
  riscv: Fix config KASAN && DEBUG_VIRTUAL

 arch/riscv/include/asm/page.h    | 2 +-
 arch/riscv/include/asm/pgtable.h | 1 +
 arch/riscv/mm/Makefile           | 3 +++
 arch/riscv/mm/kasan_init.c       | 3 +--
 arch/riscv/mm/physaddr.c         | 4 +---
 5 files changed, 7 insertions(+), 6 deletions(-)

-- 
2.32.0