CVE-2022-49329

In the Linux kernel, the following vulnerability has been resolved:

vduse: Fix NULL pointer dereference on sysfs access

The control device has no drvdata. So we will get a NULL pointer dereference when accessing control device's msg_timeout attribute via sysfs:

[ 132.841881][ T3644] BUG: kernel NULL pointer dereference, address: 00000000000000f8 [ 132.850619][ T3644] RIP: 0010:msgtimeoutshow (drivers/vdpa/vdpauser/vdusedev.c:1271) [ 132.869447][ T3644] devattrshow (drivers/base/core.c:2094) [ 132.870215][ T3644] sysfskfseqshow (fs/sysfs/file.c:59) [ 132.871164][ T3644] ? deviceremovebinfile (drivers/base/core.c:2088) [ 132.872082][ T3644] kernfsseqshow (fs/kernfs/file.c:164) [ 132.872838][ T3644] seqreaditer (fs/seqfile.c:230) [ 132.873578][ T3644] ? _vmallocareanode (mm/vmalloc.c:3041) [ 132.874532][ T3644] kernfsfopreaditer (fs/kernfs/file.c:238) [ 132.875513][ T3644] _kernelread (fs/readwrite.c:440 (discriminator 1)) [ 132.876319][ T3644] kernelread (fs/readwrite.c:459) [ 132.877129][ T3644] kernelreadfile (fs/kernelreadfile.c:94) [ 132.877978][ T3644] kernelreadfilefromfd (include/linux/file.h:45 fs/kernelreadfile.c:186) [ 132.879019][ T3644] _dosysfinitmodule (kernel/module.c:4207) [ 132.879930][ T3644] _ia32sysfinitmodule (kernel/module.c:4189) [ 132.880930][ T3644] doint80syscall32 (arch/x86/entry/common.c:112 arch/x86/entry/common.c:132) [ 132.881847][ T3644] entryINT80compat (arch/x86/entry/entry64_compat.S:419)

To fix it, don't create the unneeded attribute for control device anymore.