From bd86c69dae65de30f6d47249418ba7889809e31a Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 10 Oct 2022 14:59:02 +0900 Subject: [PATCH 1/2] NFSD: unregister shrinker when nfsd_init_net() fails syzbot is reporting UAF read at register_shrinker_prepared() [1], for commit 7746b32f467b3813 ("NFSD: add shrinker to reap courtesy clients on low memory condition") missed that nfsd4_leases_net_shutdown() from nfsd_exit_net() is called only when nfsd_init_net() succeeded. If nfsd_init_net() fails due to nfsd_reply_cache_init() failure, register_shrinker() from nfsd4_init_leases_net() has to be undone before nfsd_init_net() returns. Link: https://syzkaller.appspot.com/bug?extid=ff796f04613b4c84ad89 [1] Reported-by: syzbot Signed-off-by: Tetsuo Handa Fixes: 7746b32f467b3813 ("NFSD: add shrinker to reap courtesy clients on low memory condition") Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- fs/nfsd/nfsctl.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 6a29bcfc93909..dc74a947a440c 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1458,12 +1458,14 @@ static __net_init int nfsd_init_net(struct net *net) goto out_drc_error; retval = nfsd_reply_cache_init(nn); if (retval) - goto out_drc_error; + goto out_cache_error; get_random_bytes(&nn->siphash_key, sizeof(nn->siphash_key)); seqlock_init(&nn->writeverf_lock); return 0; +out_cache_error: + nfsd4_leases_net_shutdown(nn); out_drc_error: nfsd_idmap_shutdown(net); out_idmap_error: From 93c128e709aec23b10f3a2f78a824080d4085318 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 12 Oct 2022 14:42:54 -0400 Subject: [PATCH 2/2] nfsd: ensure we always call fh_verify_error tracepoint This is a conditional tracepoint. Call it every time, not just when nfs_permission fails. Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever --- fs/nfsd/nfsfh.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c index d73434200df98..8c52b6c9d31a2 100644 --- a/fs/nfsd/nfsfh.c +++ b/fs/nfsd/nfsfh.c @@ -392,8 +392,8 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) skip_pseudoflavor_check: /* Finally, check access permissions. */ error = nfsd_permission(rqstp, exp, dentry, access); - trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error); out: + trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error); if (error == nfserr_stale) nfsd_stats_fh_stale_inc(exp); return error;