From b31da62889e6d610114d81dc7a6edbcaa503fcf8 Mon Sep 17 00:00:00 2001 From: Li Lingfeng Date: Mon, 14 Apr 2025 22:38:52 +0800 Subject: [PATCH] nfsd: Initialize ssc before laundromat_work to prevent NULL dereference In nfs4_state_start_net(), laundromat_work may access nfsd_ssc through nfs4_laundromat -> nfsd4_ssc_expire_umount. If nfsd_ssc isn't initialized, this can cause NULL pointer dereference. Normally the delayed start of laundromat_work allows sufficient time for nfsd_ssc initialization to complete. However, when the kernel waits too long for userspace responses (e.g. in nfs4_state_start_net -> nfsd4_end_grace -> nfsd4_record_grace_done -> nfsd4_cld_grace_done -> cld_pipe_upcall -> __cld_pipe_upcall -> wait_for_completion path), the delayed work may start before nfsd_ssc initialization finishes. Fix this by moving nfsd_ssc initialization before starting laundromat_work. Fixes: f4e44b393389 ("NFSD: delay unmount source's export after inter-server copy completed.") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Signed-off-by: Li Lingfeng Signed-off-by: Chuck Lever --- fs/nfsd/nfssvc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 9b3d6cff0e1e2..8ed143ef8b411 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -396,13 +396,13 @@ static int nfsd_startup_net(struct net *net, const struct cred *cred) if (ret) goto out_filecache; +#ifdef CONFIG_NFSD_V4_2_INTER_SSC + nfsd4_ssc_init_umount_work(nn); +#endif ret = nfs4_state_start_net(net); if (ret) goto out_reply_cache; -#ifdef CONFIG_NFSD_V4_2_INTER_SSC - nfsd4_ssc_init_umount_work(nn); -#endif nn->nfsd_net_up = true; return 0; -- 2.50.1