From a99d720ed2a5258564e5e9d5f39f3184a030d354 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 2 Jun 2026 12:23:17 -0400 Subject: nfsd: widen nfsd_genl_rqstp address fields to sockaddr_storage struct nfsd_genl_rqstp declares rq_daddr and rq_saddr as plain "struct sockaddr" (16 bytes). When an IPv6 NFS client is connected, nfsd_genl_rpc_status_compose_msg() casts these fields to "struct sockaddr_in6 *" (28 bytes) and reads sin6_addr at offset 8..24, which extends 8 bytes past the end of the 16-byte sockaddr field into the adjacent rq_flags member. The 16-byte nla_put_in6_addr then ships 8 bytes of truncated IPv6 address followed by 8 bytes of rq_flags to userspace via the NFSD_A_RPC_STATUS_SADDR6/DADDR6 netlink attributes. This is reachable by any unprivileged process in the network namespace because NFSD_CMD_RPC_STATUS_GET uses GENL_CMD_CAP_DUMP without GENL_ADMIN_PERM. Fix by widening rq_daddr and rq_saddr to struct sockaddr_storage so the IPv6 casts operate within bounds, copying sizeof(struct sockaddr_storage) bytes in the memcpy calls so the full address is captured, and zero-initializing the genl_rqstp stack variable to prevent leaking uninitialized tail bytes through netlink. Fixes: bd9d6a3efa97 ("NFSD: add rpc_status netlink support") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260602-nfsd-testing-v2-5-e4ea62e3cd5c@kernel.org Signed-off-by: Chuck Lever --- fs/nfsd/nfsctl.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 5e3e60110ee6..c2ec30e6b51f 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1414,8 +1414,8 @@ static int create_proc_exports_entry(void) unsigned int nfsd_net_id; struct nfsd_genl_rqstp { - struct sockaddr rq_daddr; - struct sockaddr rq_saddr; + struct sockaddr_storage rq_daddr; + struct sockaddr_storage rq_saddr; unsigned long rq_flags; ktime_t rq_stime; __be32 rq_xid; @@ -1450,7 +1450,7 @@ static int nfsd_genl_rpc_status_compose_msg(struct sk_buff *skb, NFSD_A_RPC_STATUS_PAD)) return -ENOBUFS; - switch (genl_rqstp->rq_saddr.sa_family) { + switch (genl_rqstp->rq_saddr.ss_family) { case AF_INET: { const struct sockaddr_in *s_in, *d_in; @@ -1527,7 +1527,7 @@ int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb, list_for_each_entry_rcu(rqstp, &nn->nfsd_serv->sv_pools[i].sp_all_threads, rq_all) { - struct nfsd_genl_rqstp genl_rqstp; + struct nfsd_genl_rqstp genl_rqstp = {}; unsigned int status_counter; if (rqstp_index++ < cb->args[1]) /* already consumed */ @@ -1551,9 +1551,9 @@ int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb, genl_rqstp.rq_stime = rqstp->rq_stime; genl_rqstp.rq_opcnt = 0; memcpy(&genl_rqstp.rq_daddr, svc_daddr(rqstp), - sizeof(struct sockaddr)); + sizeof(struct sockaddr_storage)); memcpy(&genl_rqstp.rq_saddr, svc_addr(rqstp), - sizeof(struct sockaddr)); + sizeof(struct sockaddr_storage)); #ifdef CONFIG_NFSD_V4 if (rqstp->rq_vers == NFS4_VERSION && -- cgit v1.2.3