6f6f84aa21
KASAN report null-ptr-deref as follows: BUG: KASAN: null-ptr-deref in nfsd_fill_super+0xc6/0xe0 [nfsd] Write of size 8 at addr 000000000000005d by task a.out/852 CPU: 7 PID: 852 Comm: a.out Not tainted 5.18.0-rc7-dirty #66 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x34/0x44 kasan_report+0xab/0x120 ? nfsd_mkdir+0x71/0x1c0 [nfsd] ? nfsd_fill_super+0xc6/0xe0 [nfsd] nfsd_fill_super+0xc6/0xe0 [nfsd] ? nfsd_mkdir+0x1c0/0x1c0 [nfsd] get_tree_keyed+0x8e/0x100 vfs_get_tree+0x41/0xf0 __do_sys_fsconfig+0x590/0x670 ? fscontext_read+0x180/0x180 ? anon_inode_getfd+0x4f/0x70 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae This can be reproduce by concurrent operations: 1. fsopen(nfsd)/fsconfig 2. insmod/rmmod nfsd Since the nfsd file system is registered before than nfsd_net allocated, the caller may get the file_system_type and use the nfsd_net before it allocated, then null-ptr-deref occurred. So init_nfsd() should call register_filesystem() last. Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.