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| author | NeilBrown <neilb@suse.de> | 2023-09-12 11:25:00 +1000 |
|---|---|---|
| committer | Chuck Lever <chuck.lever@oracle.com> | 2023-09-12 09:39:35 -0400 |
| commit | 88956eabfdea7d01d550535af120d4ef265b1d02 (patch) | |
| tree | 053ec23c764a43da8077ddf9517b5321f02b9a9a | |
| parent | fdd2630a7398191e84822612e589062063bd4f3d (diff) | |
| download | linux-88956eabfdea7d01d550535af120d4ef265b1d02.tar.gz | |
NFSD: fix possible oops when nfsd/pool_stats is closed.
If /proc/fs/nfsd/pool_stats is open when the last nfsd thread exits, then
when the file is closed a NULL pointer is dereferenced.
This is because nfsd_pool_stats_release() assumes that the
pointer to the svc_serv cannot become NULL while a reference is held.
This used to be the case but a recent patch split nfsd_last_thread() out
from nfsd_put(), and clearing the pointer is done in nfsd_last_thread().
This is easily reproduced by running
rpc.nfsd 8 ; ( rpc.nfsd 0;true) < /proc/fs/nfsd/pool_stats
Fortunately nfsd_pool_stats_release() has easy access to the svc_serv
pointer, and so can call svc_put() on it directly.
Fixes: 9f28a971ee9f ("nfsd: separate nfsd_last_thread() from nfsd_put()")
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
| -rw-r--r-- | fs/nfsd/nfssvc.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 1582af33e204a1..c7af1095f6b549 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -1082,11 +1082,12 @@ int nfsd_pool_stats_open(struct inode *inode, struct file *file) int nfsd_pool_stats_release(struct inode *inode, struct file *file) { + struct seq_file *seq = file->private_data; + struct svc_serv *serv = seq->private; int ret = seq_release(inode, file); - struct net *net = inode->i_sb->s_fs_info; mutex_lock(&nfsd_mutex); - nfsd_put(net); + svc_put(serv); mutex_unlock(&nfsd_mutex); return ret; } |