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

From: David Hildenbrand
Date: Wed Jan 31 2024 - 04:19:08 EST

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