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[12/12] isdn/gigaset: fix usb_gigaset write_cmd result race

Message ID 2606e14cb61bc99f0f574b43ff6d9f585f199286.1413021631.git.tilman@imap.cc
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Tilman Schmidt Oct. 11, 2014, 11:46 a.m. UTC 
In usb_gigaset function gigaset_write_cmd(), the length field of
the command buffer structure could be cleared by the transmit
tasklet before it was used for the function's return value.
Fix by copying to a local variable before scheduling the tasklet.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
---
 drivers/isdn/gigaset/usb-gigaset.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/isdn/gigaset/usb-gigaset.c b/drivers/isdn/gigaset/usb-gigaset.c
index 82e91ba..a8e652d 100644
--- a/drivers/isdn/gigaset/usb-gigaset.c
+++ b/drivers/isdn/gigaset/usb-gigaset.c
@@ -497,6 +497,7 @@  static int send_cb(struct cardstate *cs, struct cmdbuf_t *cb)
 static int gigaset_write_cmd(struct cardstate *cs, struct cmdbuf_t *cb)
 {
 	unsigned long flags;
+	int len;
 
 	gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
 			   DEBUG_TRANSCMD : DEBUG_LOCKCMD,
@@ -515,10 +516,11 @@  static int gigaset_write_cmd(struct cardstate *cs, struct cmdbuf_t *cb)
 	spin_unlock_irqrestore(&cs->cmdlock, flags);
 
 	spin_lock_irqsave(&cs->lock, flags);
+	len = cb->len;
 	if (cs->connected)
 		tasklet_schedule(&cs->write_tasklet);
 	spin_unlock_irqrestore(&cs->lock, flags);
-	return cb->len;
+	return len;
 }
 
 static int gigaset_write_room(struct cardstate *cs)