From: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Thu, 30 Aug 2018 10:12:59 +1000
Subject: [PATCH] cifs: add a warning if we try to to dequeue a deleted mid
Git-commit: ddf83afb9f60ee58cdec30bb615eff65d00ba05e
Patch-mainline: v4.19-rc7
References: bsc#1144333
cifs_delete_mid() is called once we are finished handling a mid and we
expect no more work done on this mid.
Needed to fix recent commit:
commit 730928c8f4be88e9d6a027a16b1e8fa9c59fc077
("cifs: update smb2_queryfs() to use compounding")
Add a warning if someone tries to dequeue a mid that has already been
flagged to be deleted.
Also change list_del() to list_del_init() so that if we have similar bugs
resurface in the future we will not oops.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
fs/cifs/cifsglob.h | 1 +
fs/cifs/connect.c | 10 +++++++++-
fs/cifs/transport.c | 3 ++-
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 0c9ab62c3df4..9dcaed031843 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1553,6 +1553,7 @@ static inline void free_dfs_info_array(struct dfs_info3_param *param,
/* Flags */
#define MID_WAIT_CANCELLED 1 /* Cancelled while waiting for response */
+#define MID_DELETED 2 /* Mid has been dequeued/deleted */
/* Types of response buffer returned from SendReceive2 */
#define CIFS_NO_BUFFER 0 /* Response buffer not returned */
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 7aa08dba4719..e9d64c92b8da 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -659,7 +659,15 @@ dequeue_mid(struct mid_q_entry *mid, bool malformed)
mid->mid_state = MID_RESPONSE_RECEIVED;
else
mid->mid_state = MID_RESPONSE_MALFORMED;
- list_del_init(&mid->qhead);
+ /*
+ * Trying to handle/dequeue a mid after the send_recv()
+ * function has finished processing it is a bug.
+ */
+ if (mid->mid_flags & MID_DELETED)
+ printk_once(KERN_WARNING
+ "trying to dequeue a deleted mid\n");
+ else
+ list_del_init(&mid->qhead);
spin_unlock(&GlobalMid_Lock);
}
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 78f96fa3d7d9..9cc9a127749e 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -142,7 +142,8 @@ void
cifs_delete_mid(struct mid_q_entry *mid)
{
spin_lock(&GlobalMid_Lock);
- list_del(&mid->qhead);
+ list_del_init(&mid->qhead);
+ mid->mid_flags |= MID_DELETED;
spin_unlock(&GlobalMid_Lock);
DeleteMidQEntry(mid);
--
2.16.4