[Bug 260266] NFS callback RPC with negative taglen can crash client
Date: Tue, 07 Dec 2021 18:52:37 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=260266 Bug ID: 260266 Summary: NFS callback RPC with negative taglen can crash client 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 #229961 text/plain mime type: Created attachment 229961 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=229961&action=edit Crash an NFS client with a callback with a bad taglen. nfscl_docb() has a few "goto nfsmout" before it initializes retopsp, but the code after nfsmout dereferences retopsp if taglen != -1. I've attached a demo: # uname -a FreeBSD 14.0-CURRENT FreeBSD 14.0-CURRENT #130 main-n250909-08e6880c1a5c-dirty: Tue Dec 7 13:30:08 EST 2021 rtm@xxx:/usr/obj/usr/rtm/symbsd/src/riscv.riscv64/sys/RTM riscv # cc fnfs_6.c # ./a.out ... panic: Fatal page fault at 0xffffffc00021c200: 0000000000000000 --- exception 15, tval = 0 nfscl_docb() at nfscl_docb+0x1ac nfscb_program() at nfscb_program+0xee svc_run_internal() at svc_run_internal+0x810 svc_run() at svc_run+0x1a2 nfscbd_nfsd() at nfscbd_nfsd+0xce nfssvc_nfscl() at nfssvc_nfscl+0x204 sys_nfssvc() at sys_nfssvc+0xd0 do_trap_user() at do_trap_user+0x220 cpu_exception_handler_user() at cpu_exception_handler_user+0x72 -- You are receiving this mail because: You are the assignee for the bug.