6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Mason [ Upstream commit 71d068490098b1d23c63b2345e40675d3a1ca763 ] The nfsd_fh_verify and nfsd_fh_verify_err tracepoints declare the server sockaddr slot sized by xpt_remotelen but fill it from xpt_local using xpt_locallen: TP_STRUCT__entry( ... __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) ... ) TP_fast_assign( ... __assign_sockaddr(server, &rqstp->rq_xprt->xpt_local, rqstp->rq_xprt->xpt_locallen); ... ) When xpt_locallen exceeds xpt_remotelen, __assign_sockaddr's memcpy writes past the reserved ring-buffer slot. In the reverse direction (xpt_locallen < xpt_remotelen) the slot is oversized and the unwritten tail leaks prior ring-buffer contents to trace consumers. The write-past-end case is reachable on NFS/UDP. svc_xprt_set_remote() is only called from svc_tcp_accept() (net/sunrpc/svcsock.c) and from the RDMA connect path; svc_create_socket() for UDP calls only svc_xprt_set_local(), so xpt_remotelen stays 0 for the xprt's lifetime. Every fh_verify trace for an NFSv2/v3-over-UDP request then copies 16 or 28 bytes from xpt_local into a zero-byte slot. The other NFSD tracepoints that record the server address (NFSD_TRACE_PROC_CALL_FIELDS, NFSD_TRACE_PROC_RES_FIELDS, SVC_RQST_ENDPOINT_FIELDS) already size the server slot by xpt_locallen; nfsd_fh_verify and nfsd_fh_verify_err were the only exceptions. Fix by sizing the server slot with xpt_locallen so the declared slot matches the copy length. The client slot and its assignment already agree on xpt_remotelen and are left untouched. Fixes: 051382885552 ("NFSD: Instrument fh_verify()") Fixes: 948755efc951 ("NFSD: Replace dprintk() call site in fh_verify()") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-7 Signed-off-by: Chris Mason Link: https://patch.msgid.link/20260531-nfsd-testing-v1-1-7bfa481b0540@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/trace.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h index d7ed49eef5911..6e57a9dba1a59 100644 --- a/fs/nfsd/trace.h +++ b/fs/nfsd/trace.h @@ -201,7 +201,7 @@ TRACE_EVENT(nfsd_fh_verify, TP_ARGS(rqstp, fhp, type, access), TP_STRUCT__entry( __field(unsigned int, netns_ino) - __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) + __sockaddr(server, rqstp->rq_xprt->xpt_locallen) __sockaddr(client, rqstp->rq_xprt->xpt_remotelen) __field(u32, xid) __field(u32, fh_hash) @@ -240,7 +240,7 @@ TRACE_EVENT_CONDITION(nfsd_fh_verify_err, TP_CONDITION(error), TP_STRUCT__entry( __field(unsigned int, netns_ino) - __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) + __sockaddr(server, rqstp->rq_xprt->xpt_locallen) __sockaddr(client, rqstp->rq_xprt->xpt_remotelen) __field(u32, xid) __field(u32, fh_hash) -- 2.53.0