From: Shyam Prasad N <sprasad@microsoft.com>
Date: Wed, 14 Jul 2021 23:00:00 -0500
Subject: [PATCH] cifs: added WARN_ON for all the count decrements
Git-commit: 16dd9b8c31aee7ae074fa3ee36a797e9ba9f7e4f
References: bsc#1190317
Patch-mainline: v5.14-rc2
We have a few ref counters srv_count, ses_count and
tc_count which we use for ref counting. Added a WARN_ON
during the decrement of each of these counters to make
sure that they don't go below their minimum values.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
fs/cifs/connect.c | 9 +++++++++
fs/cifs/smb2ops.c | 2 ++
2 files changed, 11 insertions(+)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2691,6 +2691,9 @@ cifs_put_tcp_session(struct TCP_Server_I
return;
}
+ /* srv_count can never go negative */
+ WARN_ON(server->srv_count < 0);
+
put_net(cifs_net_ns(server));
list_del_init(&server->tcp_ses_list);
@@ -3037,6 +3040,9 @@ void cifs_put_smb_ses(struct cifs_ses *s
}
spin_unlock(&cifs_tcp_ses_lock);
+ /* ses_count can never go negative */
+ WARN_ON(ses->ses_count < 0);
+
spin_lock(&GlobalMid_Lock);
if (ses->status == CifsGood)
ses->status = CifsExiting;
@@ -3385,6 +3391,9 @@ cifs_put_tcon(struct cifs_tcon *tcon)
return;
}
+ /* tc_count can never go negative */
+ WARN_ON(tcon->tc_count < 0);
+
list_del_init(&tcon->tcon_list);
spin_unlock(&cifs_tcp_ses_lock);
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2835,6 +2835,8 @@ smb2_get_dfs_refer(const unsigned int xi
/* ipc tcons are not refcounted */
spin_lock(&cifs_tcp_ses_lock);
tcon->tc_count--;
+ /* tc_count can never go negative */
+ WARN_ON(tcon->tc_count < 0);
spin_unlock(&cifs_tcp_ses_lock);
}
kfree(utf16_path);