diff options
| author | Jeff Layton <jlayton@kernel.org> | 2023-06-16 17:51:34 -0400 |
|---|---|---|
| committer | Chuck Lever <chuck.lever@oracle.com> | 2023-06-18 12:02:40 -0400 |
| commit | ed9ab7346e908496816cffdecd46932035f66e2e (patch) | |
| tree | 581a439469c2dc6a33d7dfb1d9fef8fecc0f1c67 /fs/nfsd/nfsctl.c | |
| parent | 00a87e5d1d67ada9fc2d3a1f6407ae339b425bce (diff) | |
nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net
Commit f5f9d4a314da ("nfsd: move reply cache initialization into nfsd
startup") moved the initialization of the reply cache into nfsd startup,
but didn't account for the stats counters, which can be accessed before
nfsd is ever started. The result can be a NULL pointer dereference when
someone accesses /proc/fs/nfsd/reply_cache_stats while nfsd is still
shut down.
This is a regression and a user-triggerable oops in the right situation:
- non-x86_64 arch
- /proc/fs/nfsd is mounted in the namespace
- nfsd is not started in the namespace
- unprivileged user calls "cat /proc/fs/nfsd/reply_cache_stats"
Although this is easy to trigger on some arches (like aarch64), on
x86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the
fixed_percpu_data. That struct looks just enough like a newly
initialized percpu var to allow nfsd_reply_cache_stats_show to access
it without Oopsing.
Move the initialization of the per-net+per-cpu reply-cache counters
back into nfsd_init_net, while leaving the rest of the reply cache
allocations to be done at nfsd startup time.
Kudos to Eirik who did most of the legwork to track this down.
Cc: stable@vger.kernel.org # v6.3+
Fixes: f5f9d4a314da ("nfsd: move reply cache initialization into nfsd startup")
Reported-and-tested-by: Eirik Fuller <efuller@redhat.com>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2215429
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'fs/nfsd/nfsctl.c')
| -rw-r--r-- | fs/nfsd/nfsctl.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 1489e0b703b4..1a892a0b35de 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1505,6 +1505,9 @@ static __net_init int nfsd_init_net(struct net *net) retval = nfsd_idmap_init(net); if (retval) goto out_idmap_error; + retval = nfsd_net_reply_cache_init(nn); + if (retval) + goto out_repcache_error; nn->nfsd_versions = NULL; nn->nfsd4_minorversions = NULL; nfsd4_init_leases_net(nn); @@ -1513,6 +1516,8 @@ static __net_init int nfsd_init_net(struct net *net) return 0; +out_repcache_error: + nfsd_idmap_shutdown(net); out_idmap_error: nfsd_export_shutdown(net); out_export_error: @@ -1521,9 +1526,12 @@ out_export_error: static __net_exit void nfsd_exit_net(struct net *net) { + struct nfsd_net *nn = net_generic(net, nfsd_net_id); + + nfsd_net_reply_cache_destroy(nn); nfsd_idmap_shutdown(net); nfsd_export_shutdown(net); - nfsd_netns_free_versions(net_generic(net, nfsd_net_id)); + nfsd_netns_free_versions(nn); } static struct pernet_operations nfsd_net_ops = { |