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In-Reply-To: <871rtqg91q.fsf@dja-thinkpad.axtens.net>
From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Fri, 29 Nov 2019 13:45:30 +0100
Message-ID: <CACT4Y+axv26RvEUYkhnOkt+0pgdxkSiMVKYNvswSXaGsQLxg7g@mail.gmail.com>
Subject: Re: [PATCH v11 1/4] kasan: support backing vmalloc space with real
 shadow memory
To:     Daniel Axtens <dja@axtens.net>
Cc:     Andrey Ryabinin <aryabinin@virtuozzo.com>, Qian Cai <cai@lca.pw>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux-MM <linux-mm@kvack.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Alexander Potapenko <glider@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Vasily Gorbik <gor@linux.ibm.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Fri, Nov 29, 2019 at 1:29 PM Daniel Axtens <dja@axtens.net> wrote:
> >>> Nope, it's vm_map_ram() not being handled
> >> Another suspicious one. Related to kasan/vmalloc?
> > Very likely the same as with ion:
> >
> > # git grep vm_map_ram|grep xfs
> > fs/xfs/xfs_buf.c:                * vm_map_ram() will allocate auxiliary structures (e.g.
> > fs/xfs/xfs_buf.c:                       bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
>
> Aaargh, that's an embarassing miss.
>
> It's a bit intricate because kasan_vmalloc_populate function is
> currently set up to take a vm_struct not a vmap_area, but I'll see if I
> can get something simple out this evening - I'm away for the first part
> of next week.
>
> Do you have to do anything interesting to get it to explode with xfs? Is
> it as simple as mounting a drive and doing some I/O? Or do you need to
> do something more involved?

As simple as running syzkaller :)
with this config
https://github.com/google/syzkaller/blob/master/dashboard/config/upstream-kasan.config

> Regards,
> Daniel
>
> >
> >>
> >> BUG: unable to handle page fault for address: fffff52005b80000
> >> #PF: supervisor read access in kernel mode
> >> #PF: error_code(0x0000) - not-present page
> >> PGD 7ffcd067 P4D 7ffcd067 PUD 2cd10067 PMD 66d76067 PTE 0
> >> Oops: 0000 [#1] PREEMPT SMP KASAN
> >> CPU: 2 PID: 9211 Comm: syz-executor.2 Not tainted 5.4.0-next-20191129+ #6
> >> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> >> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> >> RIP: 0010:xfs_sb_read_verify+0xe9/0x540 fs/xfs/libxfs/xfs_sb.c:691
> >> Code: fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 1e 04 00 00 4d 8b ac 24
> >> 30 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <0f> b6
> >> 04 02 84 c0 74 08 3c 03 0f 8e ad 03 00 00 41 8b 45 00 bf 58
> >> RSP: 0018:ffffc9000a58f8d0 EFLAGS: 00010a06
> >> RAX: dffffc0000000000 RBX: 1ffff920014b1f1d RCX: ffffc9000af42000
> >> RDX: 1ffff92005b80000 RSI: ffffffff82914404 RDI: ffff88805cdb1460
> >> RBP: ffffc9000a58fab0 R08: ffff8880610cd380 R09: ffffed1005a87045
> >> R10: ffffed1005a87044 R11: ffff88802d438223 R12: ffff88805cdb1340
> >> R13: ffffc9002dc00000 R14: ffffc9000a58fa88 R15: ffff888061b5c000
> >> FS:  00007fb49bda9700(0000) GS:ffff88802d400000(0000) knlGS:0000000000000000
> >> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> CR2: fffff52005b80000 CR3: 0000000060769006 CR4: 0000000000760ee0
> >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >> PKRU: 55555554
> >> Call Trace:
> >>  xfs_buf_ioend+0x228/0xdc0 fs/xfs/xfs_buf.c:1162
> >>  __xfs_buf_submit+0x38b/0xe50 fs/xfs/xfs_buf.c:1485
> >>  xfs_buf_submit fs/xfs/xfs_buf.h:268 [inline]
> >>  xfs_buf_read_uncached+0x15c/0x560 fs/xfs/xfs_buf.c:897
> >>  xfs_readsb+0x2d0/0x540 fs/xfs/xfs_mount.c:298
> >>  xfs_fc_fill_super+0x3e6/0x11f0 fs/xfs/xfs_super.c:1415
> >>  get_tree_bdev+0x444/0x620 fs/super.c:1340
> >>  xfs_fc_get_tree+0x1c/0x20 fs/xfs/xfs_super.c:1550
> >>  vfs_get_tree+0x8e/0x300 fs/super.c:1545
> >>  do_new_mount fs/namespace.c:2822 [inline]
> >>  do_mount+0x152d/0x1b50 fs/namespace.c:3142
> >>  ksys_mount+0x114/0x130 fs/namespace.c:3351
> >>  __do_sys_mount fs/namespace.c:3365 [inline]
> >>  __se_sys_mount fs/namespace.c:3362 [inline]
> >>  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
> >>  do_syscall_64+0xfa/0x780 arch/x86/entry/common.c:294
> >>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >> RIP: 0033:0x46736a
> >> Code: 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
> >> 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d
> >> 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> >> RSP: 002b:00007fb49bda8a78 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
> >> RAX: ffffffffffffffda RBX: 00007fb49bda8af0 RCX: 000000000046736a
> >> RDX: 00007fb49bda8ad0 RSI: 0000000020000140 RDI: 00007fb49bda8af0
> >> RBP: 00007fb49bda8ad0 R08: 00007fb49bda8b30 R09: 00007fb49bda8ad0
> >> R10: 0000000000000000 R11: 0000000000000202 R12: 00007fb49bda8b30
> >> R13: 00000000004b1c60 R14: 00000000004b006d R15: 00007fb49bda96bc
> >> Modules linked in:
> >> Dumping ftrace buffer:
> >>    (ftrace buffer empty)
> >> CR2: fffff52005b80000
> >> ---[ end trace eddd8949d4c898df ]---
> >> RIP: 0010:xfs_sb_read_verify+0xe9/0x540 fs/xfs/libxfs/xfs_sb.c:691
> >> Code: fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 1e 04 00 00 4d 8b ac 24
> >> 30 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <0f> b6
> >> 04 02 84 c0 74 08 3c 03 0f 8e ad 03 00 00 41 8b 45 00 bf 58
> >> RSP: 0018:ffffc9000a58f8d0 EFLAGS: 00010a06
> >> RAX: dffffc0000000000 RBX: 1ffff920014b1f1d RCX: ffffc9000af42000
> >> RDX: 1ffff92005b80000 RSI: ffffffff82914404 RDI: ffff88805cdb1460
> >> RBP: ffffc9000a58fab0 R08: ffff8880610cd380 R09: ffffed1005a87045
> >> R10: ffffed1005a87044 R11: ffff88802d438223 R12: ffff88805cdb1340
> >> R13: ffffc9002dc00000 R14: ffffc9000a58fa88 R15: ffff888061b5c000
> >> FS:  00007fb49bda9700(0000) GS:ffff88802d400000(0000) knlGS:0000000000000000
> >> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> CR2: fffff52005b80000 CR3: 0000000060769006 CR4: 0000000000760ee0
> >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >> PKRU: 55555554
> >>
> >
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