Messages in this thread Patch in this message | | | Date | Fri, 18 Dec 2009 19:52:46 +0100 | From | Ingo Molnar <> | Subject | [GIT PULL] core kernel fixes |
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Linus,
Please pull the latest core-fixes-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git core-fixes-for-linus
Thanks,
Ingo
------------------> Thomas Gleixner (3): signal: Fix racy access to __task_cred in kill_pid_info_as_uid() signals: Fix more rcu assumptions sys: Fix missing rcu protection for __task_cred() access
kernel/signal.c | 25 ++++++++++++++----------- kernel/sys.c | 2 ++ 2 files changed, 16 insertions(+), 11 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c index 6b982f2..f67545f 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) <= @@ -1175,11 +1175,12 @@ 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; @@ -1196,14 +1197,16 @@ 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 9968c5f..bc1dc61 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -163,6 +163,7 @@ 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: @@ -200,6 +201,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) } out_unlock: read_unlock(&tasklist_lock); + rcu_read_unlock(); out: return error; }
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