[Bug 291080] nfsrv_updatelock() can use uninitialized memory -> crash

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=291080

            Bug ID: 291080
           Summary: nfsrv_updatelock() can use uninitialized memory ->
                    crash
           Product: Base System
           Version: CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: rtm@lcs.mit.edu
 Attachment #265491 text/plain
         mime type:

Created attachment 265491
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=265491&action=edit
fake client that can cause a crash in nfsrv_updatelock()

I've attached a demo fake nfs4 client that sends an OPEN rpc to the
server asking for a write delegation, and then a LOCK rpc with the
stateid from the write delegation (rather than for the open).
As a result nfsrv_updatelock() tries to use

                lop = LIST_FIRST(&stp->ls_lock);
                ...;
                if (lop->lo_lfp == lfp) {

but the ls_lock list hasn't been initialized for nfsstate stp.

# uname -a
FreeBSD xxx 16.0-CURRENT FreeBSD 16.0-CURRENT #31 main-n275523-f77ac3afe3e3:
Sun Oct 12 16:13:10 AST 2025     root@xxx:/usr/obj/usr/src/amd64.amd64/sys/
# cat /etc/exports
V4: / 127.0.0.1
/mnt 127.0.0.1
# cc nfsd535a.c
# chmod ogu+rwx /mnt
# ./a.out
...
Fatal trap 9: general protection fault while in kernel mode
rdi: deadc0dedeadc0de rsi: fffffe00d708ad28 rdx: fffffe00d708ac10
panic() at panic+0x43/frame 0xfffffe00d708aa80
trap_fatal() at trap_fatal+0x68/frame 0xfffffe00d708aaa0
calltrap() at calltrap+0x8/frame 0xfffffe00d708aaa0
--- trap 0x9, rip = 0xffffffff80a78ad4, rsp = 0xfffffe00d708ab70, rbp =
0xfffffe00d708abc0 ---
nfsrv_updatelock() at nfsrv_updatelock+0x74/frame 0xfffffe00d708abc0
nfsrv_lockctrl() at nfsrv_lockctrl+0x125f/frame 0xfffffe00d708ace0
nfsrvd_lock() at nfsrvd_lock+0x656/frame 0xfffffe00d708b1c0
nfsrvd_dorpc() at nfsrvd_dorpc+0x1672/frame 0xfffffe00d708b3d0
nfssvc_program() at nfssvc_program+0x808/frame 0xfffffe00d708b5d0
svc_run_internal() at svc_run_internal+0xaa8/frame 0xfffffe00d708b700
svc_run() at svc_run+0x280/frame 0xfffffe00d708b760
nfsrvd_nfsd() at nfsrvd_nfsd+0x3d3/frame 0xfffffe00d708b8c0
nfssvc_nfsd() at nfssvc_nfsd+0x535/frame 0xfffffe00d708bde0
sys_nfssvc() at sys_nfssvc+0xcc/frame 0xfffffe00d708be00
amd64_syscall() at amd64_syscall+0x169/frame 0xfffffe00d708bf30
fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe00d708bf30

#0  nfsrv_updatelock (stp=0xffffffd001071500, new_lopp=0xffffffc082ada998, 
    other_lopp=0xffffffc082ada880, lfp=0xffffffd001b92e80)
    at /usr/rtm/symbsd/src/sys/fs/nfsserver/nfs_nfsdstate.c:3907
#1  0xffffffc00039c4ac in nfsrv_lockctrl (vp=<optimized out>, 
    new_stpp=0xffffffc082ada9a0, new_lopp=0xffffffc082ada998, 
    cfp=0xffffffc082ada9a8, clientid=..., stateidp=0xffffffc082ada988, 
    exp=<optimized out>, nd=<optimized out>, p=0xffffffc082874140)
    at /usr/rtm/symbsd/src/sys/fs/nfsserver/nfs_nfsdstate.c:2480
#2  0xffffffc0003af518 in nfsrvd_lock (nd=0xffffffc082adb0c0, 
    isdgram=<optimized out>, vp=0xffffffd012346370, exp=0xffffffc082adaf78)
    at /usr/rtm/symbsd/src/sys/fs/nfsserver/nfs_nfsdserv.c:2630
(gdb) print lop
$2 = (struct nfslock *) 0xdeadc0dedeadc0de
(gdb) print/x stp->ls_flags 
$3 = 0x100003

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