Currently, when no active threads are running, a root user using nfsdctl
command can try to remove a particular listener from the list of previously
added ones, then start the server by increasing the number of threads,
it leads to the following problem:
[ 158.835354] refcount_t: addition on 0; use-after-free.
[ 158.835603] WARNING: CPU: 2 PID: 9145 at lib/refcount.c:25 refcount_warn_saturate+0x160/0x1a0
[ 158.836017] Modules linked in: rpcrdma rdma_cm iw_cm ib_cm ib_core nfsd auth_rpcgss nfs_acl lockd grace overlay isofs uinput snd_seq_dummy snd_hrtimer nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ip_set nf_tables qrtr sunrpc vfat fat uvcvideo videobuf2_vmalloc videobuf2_memops uvc videobuf2_v4l2 videodev videobuf2_common snd_hda_codec_generic mc e1000e snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd soundcore sg loop dm_multipath dm_mod nfnetlink vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vmw_vmci vsock xfs libcrc32c crct10dif_ce ghash_ce vmwgfx sha2_ce sha256_arm64 sr_mod sha1_ce cdrom nvme drm_client_lib drm_ttm_helper ttm nvme_core drm_kms_helper nvme_auth drm fuse
[ 158.840093] CPU: 2 UID: 0 PID: 9145 Comm: nfsd Kdump: loaded Tainted: G B W 6.13.0-rc6+ #7
[ 158.840624] Tainted: [B]=BAD_PAGE, [W]=WARN
[ 158.840802] Hardware name: VMware, Inc. VMware20,1/VBSA, BIOS VMW201.00V.24006586.BA64.2406042154 06/04/2024
[ 158.841220] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 158.841563] pc : refcount_warn_saturate+0x160/0x1a0
[ 158.841780] lr : refcount_warn_saturate+0x160/0x1a0
[ 158.842000] sp : ffff800089be7d80
[ 158.842147] x29: ffff800089be7d80 x28: ffff00008e68c148 x27: ffff00008e68c148
[ 158.842492] x26: ffff0002e3b5c000 x25: ffff600011cd1829 x24: ffff00008653c010
[ 158.842832] x23: ffff00008653c000 x22: 1fffe00011cd1829 x21: ffff00008653c028
[ 158.843175] x20: 0000000000000002 x19: ffff00008653c010 x18: 0000000000000000
[ 158.843505] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[ 158.843836] x14: 0000000000000000 x13: 0000000000000001 x12: ffff600050a26493
[ 158.844143] x11: 1fffe00050a26492 x10: ffff600050a26492 x9 : dfff800000000000
[ 158.844475] x8 : 00009fffaf5d9b6e x7 : ffff000285132493 x6 : 0000000000000001
[ 158.844823] x5 : ffff000285132490 x4 : ffff600050a26493 x3 : ffff8000805e72bc
[ 158.845174] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000098588000
[ 158.845528] Call trace:
[ 158.845658] refcount_warn_saturate+0x160/0x1a0 (P)
[ 158.845894] svc_recv+0x58c/0x680 [sunrpc]
[ 158.846183] nfsd+0x1fc/0x348 [nfsd]
[ 158.846390] kthread+0x274/0x2f8
[ 158.846546] ret_from_fork+0x10/0x20
[ 158.846714] ---[ end trace 0000000000000000 ]---
nfsd_nl_listener_set_doit() would manipulate the list of transports of
server's sv_permsocks and close the specified listener but the other
list of transports (server's sp_xprts list) would not be changed leading
to the problem above.
Instead, determined if the nfsdctl is trying to remove a listener, in
which case, delete all the existing listener transports and re-create
all-but-the-removed ones.
Fixes: 16a471177496 ("NFSD: add listener-{set,get} netlink command")
Signed-off-by: Olga Kornievskaia <okorniev@xxxxxxxxxx>
---
fs/nfsd/nfsctl.c | 41 ++++++++++++++++++-----------------------
1 file changed, 18 insertions(+), 23 deletions(-)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 95ea4393305b..079c1fe2eee7 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1918,6 +1918,7 @@ int nfsd_nl_listener_set_doit(struct sk_buff *skb, struct genl_info *info)
LIST_HEAD(permsocks);
struct nfsd_net *nn;
int err, rem;
+ bool delete = false;
mutex_lock(&nfsd_mutex);
@@ -1977,35 +1978,26 @@ int nfsd_nl_listener_set_doit(struct sk_buff *skb, struct genl_info *info)
}
}
- /* For now, no removing old sockets while server is running */
- if (serv->sv_nrthreads && !list_empty(&permsocks)) {
+ /* If we have listener transports left on permsocks list, it means
+ * we are asked to remove a listener
+ */
+ if (!list_empty(&permsocks)) {
list_splice_init(&permsocks, &serv->sv_permsocks);
- spin_unlock_bh(&serv->sv_lock);
- err = -EBUSY;
- goto out_unlock_mtx;
+ delete = true;
}
+ spin_unlock_bh(&serv->sv_lock);
- /* Close the remaining sockets on the permsocks list */
- while (!list_empty(&permsocks)) {
- xprt = list_first_entry(&permsocks, struct svc_xprt, xpt_list);
- list_move(&xprt->xpt_list, &serv->sv_permsocks);
-
- /*
- * Newly-created sockets are born with the BUSY bit set. Clear
- * it if there are no threads, since nothing can pick it up
- * in that case.
+ /* Not removing old listener transports while server is running */
+ if (serv->sv_nrthreads) {
+ err = -EBUSY;
+ goto out_unlock_mtx;
+ } else if (delete) {
+ /* since we can't delete a single entry, we will destroy
+ * all remaining listeners and recreate the list
*/
- if (!serv->sv_nrthreads)
- clear_bit(XPT_BUSY, &xprt->xpt_flags);
-
- set_bit(XPT_CLOSE, &xprt->xpt_flags);
- spin_unlock_bh(&serv->sv_lock);
- svc_xprt_close(xprt);
- spin_lock_bh(&serv->sv_lock);
+ svc_xprt_destroy_all(serv, net);
}
- spin_unlock_bh(&serv->sv_lock);
-
/* walk list of addrs again, open any that still don't exist */
nlmsg_for_each_attr(attr, info->nlhdr, GENL_HDRLEN, rem) {
struct nlattr *tb[NFSD_A_SOCK_MAX + 1];
@@ -2031,6 +2023,9 @@ int nfsd_nl_listener_set_doit(struct sk_buff *skb, struct genl_info *info)
xprt = svc_find_listener(serv, xcl_name, net, sa);
if (xprt) {
+ if (delete)
+ WARN_ONCE("Transport type=%s already exists\n",
+ xcl_name);
svc_xprt_put(xprt);
continue;
}
