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Subject[055/264] USB: pid_ns: ensure pid is not freed during kill_pid_info_as_uid
3.1-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Serge Hallyn <serge.hallyn@canonical.com>

commit aec01c5895051849ed842dc5b8794017a7751f28 upstream.

Alan Stern points out that after spin_unlock(&ps->lock) there is no
guarantee that ps->pid won't be freed. Since kill_pid_info_as_uid() is
called after the spin_unlock(), the pid passed to it must be pinned.

Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/core/devio.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -407,7 +407,7 @@ static void async_completed(struct urb *
sinfo.si_errno = as->status;
sinfo.si_code = SI_ASYNCIO;
sinfo.si_addr = as->userurb;
- pid = as->pid;
+ pid = get_pid(as->pid);
uid = as->uid;
euid = as->euid;
secid = as->secid;
@@ -422,9 +422,11 @@ static void async_completed(struct urb *
cancel_bulk_urbs(ps, as->bulk_addr);
spin_unlock(&ps->lock);

- if (signr)
+ if (signr) {
kill_pid_info_as_uid(sinfo.si_signo, &sinfo, pid, uid,
euid, secid);
+ put_pid(pid);
+ }

wake_up(&ps->wait);
}



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