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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-19 09:47:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-19 09:47:34 -0800
commit10e5453ffa0d04a2eda3cda3f55b88cb9c04595f (patch)
treedef247dc399549bc1359fe9d1faa49c621f8890d /kernel
parent3cd312c3e887b4bee2d94668a481b3d19c07732c (diff)
parentd4581a239a40319205762b76c01eb6363f277efa (diff)
downloadvexpress-lsk-10e5453ffa0d04a2eda3cda3f55b88cb9c04595f.tar.gz
Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sys: Fix missing rcu protection for __task_cred() access signals: Fix more rcu assumptions signal: Fix racy access to __task_cred in kill_pid_info_as_uid()
Diffstat (limited to 'kernel')
-rw-r--r--kernel/signal.c25
-rw-r--r--kernel/sys.c2
2 files changed, 16 insertions, 11 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 1814e68e4de..d09692b4037 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -218,13 +218,13 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
struct user_struct *user;
/*
- * We won't get problems with the target's UID changing under us
- * because changing it requires RCU be used, and if t != current, the
- * caller must be holding the RCU readlock (by way of a spinlock) and
- * we use RCU protection here
+ * Protect access to @t credentials. This can go away when all
+ * callers hold rcu read lock.
*/
+ rcu_read_lock();
user = get_uid(__task_cred(t)->user);
atomic_inc(&user->sigpending);
+ rcu_read_unlock();
if (override_rlimit ||
atomic_read(&user->sigpending) <=
@@ -1179,11 +1179,12 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
int ret = -EINVAL;
struct task_struct *p;
const struct cred *pcred;
+ unsigned long flags;
if (!valid_signal(sig))
return ret;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = pid_task(pid, PIDTYPE_PID);
if (!p) {
ret = -ESRCH;
@@ -1199,14 +1200,16 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
ret = security_task_kill(p, info, sig, secid);
if (ret)
goto out_unlock;
- if (sig && p->sighand) {
- unsigned long flags;
- spin_lock_irqsave(&p->sighand->siglock, flags);
- ret = __send_signal(sig, info, p, 1, 0);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
+
+ if (sig) {
+ if (lock_task_sighand(p, &flags)) {
+ ret = __send_signal(sig, info, p, 1, 0);
+ unlock_task_sighand(p, &flags);
+ } else
+ ret = -ESRCH;
}
out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
diff --git a/kernel/sys.c b/kernel/sys.c
index 20ccfb5da6a..26a6b73a6b8 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -162,6 +162,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
if (niceval > 19)
niceval = 19;
+ rcu_read_lock();
read_lock(&tasklist_lock);
switch (which) {
case PRIO_PROCESS:
@@ -199,6 +200,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
}
out_unlock:
read_unlock(&tasklist_lock);
+ rcu_read_unlock();
out:
return error;
}