[PATCH 07/10] Staging: android: task_get_unused_fd_flags: fix the wrong usage of tsk->signal

Greg Kroah-Hartman
2009-01-28T23:31:41Z

From: Oleg Nesterov <oleg@redhat.com>

Compile tested.

task_struct->signal is not protected by RCU, the code is bogus.
Change the code to take ->siglock to pin ->signal.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Brian Swetland <swetland@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/staging/android/binder.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index ab014bc..758131c 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -319,6 +319,7 @@ int task_get_unused_fd_flags(struct task_struct *tsk, int flags)
int fd, error;
struct fdtable *fdt;
unsigned long rlim_cur;
+ unsigned long irqs;

if (files == NULL)
return -ESRCH;
@@ -335,12 +336,11 @@ repeat:
* N.B. For clone tasks sharing a files structure, this test
* will limit the total number of files that can be opened.
*/
- rcu_read_lock();
- if (tsk->signal)
+ rlim_cur = 0;
+ if (lock_task_sighand(tsk, &irqs)) {
rlim_cur = tsk->signal->rlim[RLIMIT_NOFILE].rlim_cur;
- else
- rlim_cur = 0;
- rcu_read_unlock();
+ unlock_task_sighand(tsk, &irqs);
+ }
if (fd >= rlim_cur)
goto out;

--
1.6.0.2