Re: [Syzkaller & bisect] There is BUG: unable to handle kernel paging request in fuse_copy_one in intel-6.8-rc2

[David Hildenbrand <david@redhat.com>]

On 31.01.24 03:01, Pengfei Xu wrote:
> Hi Mike,
> 
> Greeting!
> 
> There is "unable to handle kernel paging request in fuse_copy_one" BUG in
> intel-6.8-rc2:
> 
> All detailed info: https://github.com/xupengfe/syzkaller_logs/tree/main/240130_184751_fuse_copy_one
> Syzkaller reproduced code: https://github.com/xupengfe/syzkaller_logs/blob/main/240130_184751_fuse_copy_one/repro.c
> Syzkaller repro syscall steps: https://github.com/xupengfe/syzkaller_logs/blob/main/240130_184751_fuse_copy_one/repro.prog
> Bisect info: https://github.com/xupengfe/syzkaller_logs/blob/main/240130_184751_fuse_copy_one/bisect_info.log
> Issue dmesg: https://github.com/xupengfe/syzkaller_logs/blob/main/240130_184751_fuse_copy_one/41bccc98fb7931d63d03f326a746ac4d429c1dd3_dmesg.log
> bzImage: https://github.com/xupengfe/syzkaller_logs/raw/main/240130_184751_fuse_copy_one/bzImage_v6.8-rc2.tar.gz
> Kconfig(make olddefconfig): https://github.com/xupengfe/syzkaller_logs/blob/main/240130_184751_fuse_copy_one/kconfig_origin
> 
> Bisected and found first bad commit is:
> b758fe6df50da mm/secretmem: make it on by default

Sounds like we manage to access a page that has its direct map removed 
-- either because it's actual secretmem memory, or because we fail to 
restore the direct map.

> 
> Reverted above commit on top of v6.8-rc2, above issue was gone.
> 
> Syzkaller rpro.report: https://github.com/xupengfe/syzkaller_logs/blob/main/240130_184751_fuse_copy_one/repro.report
> BUG: unable to handle page fault for address: ffff8880119a5040
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 9c01067 P4D 9c01067 PUD 9c02067 PMD 11d62063 PTE 800fffffee65a060
> Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
> CPU: 1 PID: 751 Comm: syz-executor148 Not tainted 6.8.0-rc1-2024-01-22-intel-next-e32989111619+ #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38
> Code: f7 e7 49 01 d5 eb ba 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f8 48 89 d1 <f3> a4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90
> RSP: 0018:ffff88800e2af878 EFLAGS: 00010293
> RAX: ffff88800e2afa80 RBX: 0000000000000010 RCX: 0000000000000010
> RDX: 0000000000000010 RSI: ffff8880119a5040 RDI: ffff88800e2afa80
> RBP: ffff88800e2af8c0 R08: ffff888013b14a00 R09: 0000000000000001
> R10: fffffbfff0ef68c4 R11: ffffffff877b4627 R12: ffff88800e2af8f8
> R13: ffff88800e2af938 R14: ffff88800e2afc38 R15: 0000000000000010
> FS:  000000000100c480(0000) GS:ffff88806cd00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffff8880119a5040 CR3: 000000000f6ca000 CR4: 0000000000750ef0
> PKRU: 55555554
> Call Trace:
>   <TASK>
>   fuse_copy_one+0x11e/0x1a0 fs/fuse/dev.c:1007
>   fuse_dev_do_write+0x186/0x26b0 fs/fuse/dev.c:1863
>   fuse_dev_write+0x15f/0x200 fs/fuse/dev.c:1960
>   call_write_iter include/linux/fs.h:2085 [inline]
>   new_sync_write fs/read_write.c:497 [inline]
>   vfs_write fs/read_write.c:590 [inline]
>   vfs_write+0xa5a/0x1120 fs/read_write.c:570
>   ksys_write+0x13a/0x270 fs/read_write.c:643
>   __do_sys_write fs/read_write.c:655 [inline]
>   __se_sys_write fs/read_write.c:652 [inline]
>   __x64_sys_write+0x7c/0xc0 fs/read_write.c:652
>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>   do_syscall_64+0x74/0x150 arch/x86/entry/common.c:83
>   entry_SYSCALL_64_after_hwframe+0x6e/0x76
> RIP: 0033:0x4504ed
> Code: db 48 89 d8 5b 5d 41 5c 41 5d 41 5e c3 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff15c70d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004504ed
> RDX: 0000000000000050 RSI: 0000000020000040 RDI: 0000000000000003
> RBP: 00000000ffffffff R08: 00000000ffffffff R09: 0000000000000000
> R10: 00007fff15c70d70 R11: 0000000000000246 R12: 0000000000412190
> R13: 0000000000000000 R14: 00000000004004e8 R15: 0000000000000000
>   </TASK>
> Modules linked in:
> CR2: ffff8880119a5040
> ---[ end trace 0000000000000000 ]---
> 
> 
> Hope it's helpful.
> 
> ---
> 
> If you don't need the following environment to reproduce the problem or if you
> already have one reproduced environment, please ignore the following information.
> 
> How to reproduce:
> git clone https://gitlab.com/xupengfe/repro_vm_env.git
> cd repro_vm_env
> tar -xvf repro_vm_env.tar.gz
> cd repro_vm_env; ./start3.sh  // it needs qemu-system-x86_64 and I used v7.1.0
>    // start3.sh will load bzImage_2241ab53cbb5cdb08a6b2d4688feb13971058f65 v6.2-rc5 kernel
>    // You could change the bzImage_xxx as you want
>    // Maybe you need to remove line "-drive if=pflash,format=raw,readonly=on,file=./OVMF_CODE.fd \" for different qemu version
> You could use below command to log in, there is no password for root.
> ssh -p 10023 root@localhost
> 
> After login vm(virtual machine) successfully, you could transfer reproduced
> binary to the vm by below way, and reproduce the problem in vm:
> gcc -pthread -o repro repro.c
> scp -P 10023 repro root@localhost:/root/
> 
> Get the bzImage for target kernel:
> Please use target kconfig and copy it to kernel_src/.config
> make olddefconfig
> make -jx bzImage           //x should equal or less than cpu num your pc has
> 
> Fill the bzImage file into above start3.sh to load the target kernel in vm.
> 
> 
> Tips:
> If you already have qemu-system-x86_64, please ignore below info.
> If you want to install qemu v7.1.0 version:
> git clone https://github.com/qemu/qemu.git
> cd qemu
> git checkout -f v7.1.0
> mkdir build
> cd build
> yum install -y ninja-build.x86_64
> yum -y install libslirp-devel.x86_64
> ../configure --target-list=x86_64-softmmu --enable-kvm --enable-vnc --enable-gtk --enable-sdl --enable-usb-redir --enable-slirp
> make
> make install
> 
> Best Regards,
> Thanks!
> 

-- 
Cheers,

David / dhildenb