Date: Wed, 24 Nov 2021 09:47:47 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 260012] NFS v4 client can crash server with a bad LAYOUTRETURN RPC Message-ID: <bug-260012-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D260012 Bug ID: 260012 Summary: NFS v4 client can crash server with a bad LAYOUTRETURN RPC 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 #229690 text/plain mime type: Created attachment 229690 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D229690&action= =3Dedit An NFS client that crashes the server with a bad LAYOUTRETURN. If an NFS v4 client sends a LAYOUTRETURN RPC with lr_returntype of NFSV4LAYOURRET_FILE and an lrf_body<> size <=3D 0, nfsrvd_layoutreturn() will pass a NULL layp to nfsrv_layoutreturn(). If the RPC also has layouttype=3D=3DNFSV4LAYOUT_FLEXFILE (4), nfsrv_layoutreturn() will call nfsrv_flexlayouterr(). The latter dereferences layp (as tl) without checking for NULL. I've attached a demo: # uname -a FreeBSD 14.0-CURRENT FreeBSD 14.0-CURRENT #96 main-n250901-77e3db078984-di= rty: Tue Nov 23 16:58:28 EST 2021=20=20=20=20 rtm@xxx:/usr/obj/usr/rtm/symbsd/src/riscv.riscv64/sys/RTM riscv # cc fnfsd_1.c # ./a.out ... nfsrv_layoutreturn: updatemdsattr failed=3D2 panic: Fatal page fault at 0xffffffc00025ce8e: 0000000000000000 cpuid =3D 0 time =3D 1637591542 KDB: stack backtrace: db_trace_self() at db_trace_self db_trace_self_wrapper() at db_trace_self_wrapper+0x38 kdb_backtrace() at kdb_backtrace+0x2c vpanic() at vpanic+0x154 panic() at panic+0x2a page_fault_handler() at page_fault_handler+0x1ee do_trap_supervisor() at do_trap_supervisor+0x76 cpu_exception_handler_supervisor() at cpu_exception_handler_supervisor+0x70 --- exception 13, tval =3D 0 nfsrv_layoutreturn() at nfsrv_layoutreturn+0xa6 nfsrvd_layoutreturn() at nfsrvd_layoutreturn+0x35c nfsrvd_dorpc() at nfsrvd_dorpc+0x154c nfssvc_program() at nfssvc_program+0x5a4 svc_run_internal() at svc_run_internal+0x808 svc_run() at svc_run+0x1a8 nfsrvd_nfsd() at nfsrvd_nfsd+0x30e nfssvc_nfsd() at nfssvc_nfsd+0x386 sys_nfssvc() at sys_nfssvc+0xd0 do_trap_user() at do_trap_user+0x206 cpu_exception_handler_user() at cpu_exception_handler_user+0x72 --=20 You are receiving this mail because: You are the assignee for the bug.=
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