The patch titled
pids: sys_getpgid: fix unsafe *pid usage, s/tasklist/rcu/
has been removed from the -mm tree. Its filename was
pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: pids: sys_getpgid: fix unsafe *pid usage, s/tasklist/rcu/
From: Oleg Nesterov <oleg@xxxxxxxxxx>
1. sys_getpgid() needs rcu_read_lock() to derive the pgrp _nr, even if
the task is current, otherwise we can race with another thread which
does sys_setpgid().
2. Use rcu_read_lock() instead of tasklist_lock when pid != 0, make sure
that we don't use the NULL pid if the task exits right after successful
find_task_by_vpid().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 36 +++++++++++++++++++++---------------
1 file changed, 21 insertions(+), 15 deletions(-)
diff -puN kernel/sys.c~pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu kernel/sys.c
--- a/kernel/sys.c~pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu
+++ a/kernel/sys.c
@@ -991,31 +991,37 @@ out:
asmlinkage long sys_getpgid(pid_t pid)
{
+ struct task_struct *p;
+ struct pid *grp;
+ int retval;
+
+ rcu_read_lock();
if (!pid)
- return task_pgrp_vnr(current);
+ grp = task_pgrp(current);
else {
- int retval;
- struct task_struct *p;
-
- read_lock(&tasklist_lock);
- p = find_task_by_vpid(pid);
retval = -ESRCH;
- if (p) {
- retval = security_task_getpgid(p);
- if (!retval)
- retval = task_pgrp_vnr(p);
- }
- read_unlock(&tasklist_lock);
- return retval;
+ p = find_task_by_vpid(pid);
+ if (!p)
+ goto out;
+ grp = task_pgrp(p);
+ if (!grp)
+ goto out;
+
+ retval = security_task_getpgid(p);
+ if (retval)
+ goto out;
}
+ retval = pid_vnr(grp);
+out:
+ rcu_read_unlock();
+ return retval;
}
#ifdef __ARCH_WANT_SYS_GETPGRP
asmlinkage long sys_getpgrp(void)
{
- /* SMP - assuming writes are word atomic this is fine */
- return task_pgrp_vnr(current);
+ return sys_getpgid(0);
}
#endif
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
posix-timers-bug-10460-discard-the-pending-signal-when-the-timer-is-destroyed.patch
workqueue-remove-redundant-function-invocation.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
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