Message-ID: <CAOUHufZa9G2VDHLPsNmp3yRyXqYCE-3-nT6P7+uf-gbgyOHXYQ@mail.gmail.com>
Date:   Wed, 15 Jun 2022 15:16:59 -0600
From:   Yu Zhao <yuzhao@...gle.com>
To:     Liam Howlett <liam.howlett@...cle.com>
Cc:     Qian Cai <quic_qiancai@...cinc.com>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v9 28/69] mm/mmap: reorganize munmap to use maple states

On Wed, Jun 15, 2022 at 1:05 PM Yu Zhao <yuzhao@...gle.com> wrote:
>
> On Wed, Jun 15, 2022 at 12:55 PM Liam Howlett <liam.howlett@...cle.com> wrote:
> >
> > * Yu Zhao <yuzhao@...gle.com> [220615 14:08]:
> > > On Wed, Jun 15, 2022 at 8:25 AM Liam Howlett <liam.howlett@...cle.com> wrote:
> > > >
> > > > * Yu Zhao <yuzhao@...gle.com> [220611 17:50]:
> > > > > On Sat, Jun 11, 2022 at 2:11 PM Yu Zhao <yuzhao@...gle.com> wrote:
> > > > > >
> > > > > > On Mon, Jun 6, 2022 at 10:40 AM Qian Cai <quic_qiancai@...cinc.com> wrote:
> > > > > > >
> > > > > > > On Mon, Jun 06, 2022 at 04:19:52PM +0000, Liam Howlett wrote:
> > > > > > > > Does your syscall fuzzer create a reproducer?  This looks like arm64
> > > > > > > > and says 5.18.0-next-20220603 again.  Was this bisected to the patch
> > > > > > > > above?
> > > > > > >
> > > > > > > This was triggered by running the fuzzer over the weekend.
> > > > > > >
> > > > > > > $ trinity -C 160
> > > > > > >
> > > > > > > No bisection was done. It was only brought up here because the trace
> > > > > > > pointed to do_mas_munmap() which was introduced here.
> > > > > >
> > > > > > Liam,
> > > > > >
> > > > > > I'm getting a similar crash on arm64 -- the allocator is madvise(),
> > > > > > not mprotect(). Please take a look.
> > > > >
> > > > > Another crash on x86_64, which seems different:
> > > >
> > > > Thanks for this.  I was able to reproduce the other crashes that you and
> > > > Qian reported.  I've sent out a patch set to Andrew to apply to the
> > > > branch which includes the fix for them and an unrelated issue discovered
> > > > when I wrote the testcases to cover what was going on here.
> > >
> > > Thanks. I'm restarting the test and will report the results in a few hours.
> > >
> > > > > BUG: KASAN: slab-out-of-bounds in mab_mas_cp+0x2d9/0x6c0
> > > > > Write of size 136 at addr ffff88c5a2319c80 by task stress-ng/18461
> > >                                                        ^^^^^^^^^
> > >
> > > > As for this crash, I was unable to reproduce and the code I just sent
> > > > out changes this code a lot.  Was this running with "trinity -c madvise"
> > > > or another use case/fuzzer?
> > >
> > > This is also stress-ng (same as the one on arm64). The test stopped
> > > before it could try syzkaller (fuzzer).
> >
> > Thanks.  What are the arguments to stress-ng you use?  I've run
> > "stress-ng --class vm -a 20 -t 600s --temp-path /tmp" until it OOMs on
> > my vm, but it only has 8GB of ram.
>
> Yes, I used the same parameters with 512GB of RAM, and the kernel with
> KASAN and other debug options.

Sorry, Liam. I got the same crash :(

9d27f2f1487a (tag: mm-everything-2022-06-14-19-05, akpm/mm-everything)
00d4d7b519d6 fs/userfaultfd: Fix vma iteration in mas_for_each() loop
55140693394d maple_tree: Make mas_prealloc() error checking more generic
2d7e7c2fcf16 maple_tree: Fix mt_destroy_walk() on full non-leaf non-alloc nodes
4d4472148ccd maple_tree: Change spanning store to work on larger trees
ea36bcc14c00 test_maple_tree: Add tests for preallocations and large
spanning writes
0d2aa86ead4f mm/mlock: Drop dead code in count_mm_mlocked_page_nr()

==================================================================
BUG: KASAN: slab-out-of-bounds in mab_mas_cp+0x2d9/0x6c0
Write of size 136 at addr ffff88c35a3b9e80 by task stress-ng/19303

CPU: 66 PID: 19303 Comm: stress-ng Tainted: G S        I       5.19.0-smp-DEV #1
Call Trace:
 <TASK>
 dump_stack_lvl+0xc5/0xf4
 print_address_description+0x7f/0x460
 print_report+0x10b/0x240
 ? mab_mas_cp+0x2d9/0x6c0
 kasan_report+0xe6/0x110
 ? mast_spanning_rebalance+0x2634/0x29b0
 ? mab_mas_cp+0x2d9/0x6c0
 kasan_check_range+0x2ef/0x310
 ? mab_mas_cp+0x2d9/0x6c0
 ? mab_mas_cp+0x2d9/0x6c0
 memcpy+0x44/0x70
 mab_mas_cp+0x2d9/0x6c0
 mas_spanning_rebalance+0x1a3e/0x4f90
 ? stack_trace_save+0xca/0x160
 ? stack_trace_save+0xca/0x160
 mas_wr_spanning_store+0x16c5/0x1b80
 mas_wr_store_entry+0xbf9/0x12e0
 mas_store_prealloc+0x205/0x3c0
 do_mas_align_munmap+0x6cf/0xd10
 do_mas_munmap+0x1bb/0x210
 ? down_write_killable+0xa6/0x110
 __vm_munmap+0x1c4/0x270
 __x64_sys_munmap+0x60/0x70
 do_syscall_64+0x44/0xa0
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x589827
Code: 00 00 00 48 c7 c2 98 ff ff ff f7 d8 64 89 02 48 c7 c0 ff ff ff
ff eb 85 66 2e 0f 1f 84 00 00 00 00 00 90 b8 0b 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 98 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffee601ec08 EFLAGS: 00000206 ORIG_RAX: 000000000000000b
RAX: ffffffffffffffda RBX: 0000400000000000 RCX: 0000000000589827
RDX: 0000000000000000 RSI: 00007ffffffff000 RDI: 0000000000000000
RBP: 00000000004cf000 R08: 00007ffee601ec40 R09: 0000000000923bf0
R10: 0000000000000008 R11: 0000000000000206 R12: 0000000000001000
R13: 00000000004cf040 R14: 0000000000000002 R15: 00007ffee601ed58
 </TASK>

Allocated by task 19303:
 __kasan_slab_alloc+0xaf/0xe0
 kmem_cache_alloc_bulk+0x261/0x360
 mas_alloc_nodes+0x2d7/0x4d0
 mas_preallocate+0xe2/0x230
 do_mas_align_munmap+0x1ce/0xd10
 do_mas_munmap+0x1bb/0x210
 __vm_munmap+0x1c4/0x270
 __x64_sys_munmap+0x60/0x70
 do_syscall_64+0x44/0xa0
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88c35a3b9e00
 which belongs to the cache maple_node of size 256
The buggy address is located 128 bytes inside of
 256-byte region [ffff88c35a3b9e00, ffff88c35a3b9f00)

The buggy address belongs to the physical page:
page:00000000325428b6 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x435a3b9
flags: 0x1400000000000200(slab|node=1|zone=1)
raw: 1400000000000200 ffffea010d71a5c8 ffffea010d71dec8 ffff88810004ff00
raw: 0000000000000000 ffff88c35a3b9000 0000000100000008 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88c35a3b9e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88c35a3b9e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88c35a3b9f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88c35a3b9f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88c35a3ba000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

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